You could also ask: “Why are there so many audio formats? Why are there so many video formats?” And so on.

The reason is different people have different ideas on what is the best way to do things.

xkcd: Standards

I wouldn’t worry too much about the package manager, just worry about whether the distro has a good package repository. If it has all the software you want to use, then use it. In my opinion, most package managers (dnf, apt, pacman, xbmp) are basically the same, and you would only notice a big difference if you ever tried to make your own package for your own software.

That said, a few package managers are very different from all the rest:

• Crux OS “prt-get”: simple and stupid: just downloads and installs tar archives.
• Gentoo “emerge”: builds all software from source code when you install it. This provides some guarantees that the source code was not tampered with by the distro maintainers, this is great if you need to review all of the source code that is running on your system, but terrible for most people who don’t want to spend so much computing power on compiling stuff every time you do a software update.
• Nix and Guix: creates its own blockchain-like database of isolated package dependency chains on your system, allowing you to instantly roll-back to the previous set of installed packages if you ever install something that breaks your system. It also guarantees that the software can be checked bit-for-bit (using SHA hash) traced back to the exact version and dependencies of the source code that built it. Nix and Guix packages also live peacefully side-by-side with any other package manager since all Nix/Guix apps are completely self-contained within its own database. In a way, it is sort of like one big AppImage or Docker container, but you can just keep adding or removing stuff to it as often as you want.
• Silverblue, SteamOS, VanillaOS, BlendOS, CarbonOS: distributes “immutable images,” so it is impossible modify the operating system at all. Updates will ship an entirely new operating system with all packages built-in. However you are allowed to install software into your home directory, and you can install FlatPacks and AppImages. This provides a great deal of security in exchange for a tiny bit of inconvenience.

My personal preference: I use ordinary Debian or Ubuntu to install the critical software that needs to be stable and reliable, and I use Guix OS on the side to install the bleeding-edge things that might break a lot.

Oh no, there are 5 package managers out there and they’re all wildly different

I know! I’ll make a standard, universal package manager that’ll be better than all the others that everyone will use!

There are now 6 different package managers

Some package managers do have differences that justify a separate project (nix, gentoo’s portage, etc).

For others, sometimes package managers are very similar feature-wise. But some developers would rather remake the thing because they would understand their code a lot better than someone else’s. Or because it would be far easier for them to customize rather than extend another project.

Imo it is developer laziness. Being able to use other people’s work is a valuable skill. But then again, this is open source, and people are free to develop the software they want the way they want.

Because people will never agree on a single one, and it’s FOSS so nothing is forced. I for one am glad I don’t have to use apt because I prefer pacman, just as I am glad someone who doesn’t want to use an Arch-derivative has Debian and apt to fall back on.

Because linux runs on an incredible amount of platforms with an incredible amount of hardware targets and platform goals.

It runs on every supercomputer and every raspberry pi and every android phone, as well as most web servers and almost every steamdeck.

Use cases are so dramatically different there will always be multiple distributions with their own needs for package managers.

Any “why are there too many X’s on Linux” (where X is package manager, desktop environment, init system etc) appear to stem from the silly assumption that there happens to be an already built operating system called Linux and all these people are forking it and putting in their own stuff for the sake of their own egos and nothing else.

When really, the answer fundamentally boils down to either one of two things: either it doesn’t exist yet, or the existing solution fails to meet a need. Linux, itself, is merely a kernel; it didn’t come with a package manager or desktop environment. Those things all had to be made by separate parties and there isn’t always agreement on how best to do them.

As a Guix user, I believe the Guix package manager has advantages over “traditional” GNU/Linux package managers, as well as other so-called “universal package managers” such as Flatpak.

There are many different “X” because people have different tastes in their choice of “X”. I like KDE, the next guy likes Gnome. I like Apt, but I might like whatever NIXOS uses, others like Yum or DNF. I kinda like the idea behind GoboLinux, probably because I was a MAC OSx user for a long while.

I think a lot of what drives the creation of redundant open source tools is that the urge to address a matter of personal taste meets the urge to start a new project, so people create new things that are different in key ways from older ones, but not necessarily better, and not necessarily even different enough to justify the amount of work that goes into them.

In some ways it feels a lot easier to start a new project then to build off an existing one:

• You don’t have to familiarize yourself with the old code, which may be in a language you don’t know or don’t like

• You don’t have to deal with the existing maintainers, who may or may not be supportive of the changes you want to make

• You don’t have to support use cases that don’t matter to you personally

Are they so different that it’s justified to have so many different distributions?

Linux isn’t a project its a source compatible ecosystem. A parts bin out of which different people assemble different things. The parts being open source means you don’t need anyone’s permission or justification to make something different out of them.

From these many and varied efforts comes life, vitality, interest, intellectual investment. You can’t just take the current things you like best and say well what if we all worked on THOSE when many of them wouldn’t even have existed save for the existence of a vital ecosystem that supported experimentation and differentiation.

If we really believed in only pulling together maybe you would be developing in cobol on your dos workstation.

Using Arch in a distrobox, no difference, but the AUR is convienient.

Imagine having only one option, and that option is dnf. I’m out. I don’t want Linux anymore.

People have different opinions on how packages should be managed. Of course, there are some package managers which are very similar to each other (DNF and zypper have the same backend), but they can also get really different (Nix/Guix and pacman are basically completely opposite in philosophy). It comes down to preference, and you can’t force anything.

Some of them are more or less historic (for example rpm/dnf and dpkg/apt), where they were developed at a similar time by unrelated projects and have just carried on separately ever since.

Others have been developed to represent very different approaches (such as portage, which is based on the traditional BSD way of managing software by building from source, or snap and flatpak, which containerise applications).

The multitude of systems don’t really cause as many problems as you’d think. As a rule, non-containerised packages need to be custom-built for each distro anyway, so it doesn’t really make any difference which packaging tool is chosen by that distro. That is, you can’t really take a debian .deb package and expect it to work properly on Fedora, even if you install dpkg/apt first.