Creating packages for various distros is not your job as a software developer, and it never was intended to be your job in the first place. At least part of this stance is based on a misunderstanding of how Linux package manager style software distribution works.
You most likely don't have experience creating and maintaining packages for every distro that exists, expecting you to be able to do this would be silly. Typically the users or developers of the countless different distros will be who handles packaging your software though, not yourself!
As a developer you just need to provide the source code, use a standardized build system such as make, cmake, meson, cargo, etc, and a list of libraries that your software depends on. If you do these things, creating a distro specific package for your software will be totally trivial for whoever feels like doing it and contributing to their distro's repo. Most distros have decades worth of tooling accumulated to make packaging software that uses standard build systems absolutely trivial!
Optionally, you can provide a flatpak image (or similar) for users who want to circumvent the system package manager.
Yes, it is my job as a software developer to distribute software to my users. Having distributions pick-up my software and distribute it themselves is a plus, but until my application has thousands of users that won't happen.
And in order to reach that "thousands of users" my users do need to be able to actually use my application (open source or not); this means either I or them has to do all that work...
So yes, one needs to "have experience in creating and maintaining packages for every distribution that exists"; or as I've proposed, just skip all this hassle and provide single binary executables for the platforms (not distributions) that one supports.
I haven't tried submitting any programs I wrote to Linux distributions, so I don't know how easy it is to find people in Debian, Fedora, and possibly OpenSUSE to package an app with no users yet, or to write your own OpenSUSE or Ubuntu PPA or Arch AUR package to distribute your app. Nonetheless I hear horror stories like https://lwn.net/Articles/884301/ saying that new packages have been waiting for up to 11 months to be reviewed. (Right now, https://ftp-master.debian.org/new.html has 55 packages down from 208, and 9 of the 55 packages have been waiting for over a month to be reviewed.)
You seem to have misunderstood what I was saying. I never said its not your job to distribute your software to your users in general, I said it is not your job to distribute via distro specific packages and repos. Even if you wanted to do this you can't since you don't have the necessary permissions to contribute code to most or even any of the repos in question.
I am not against providing a static binary or image (or whatever) by the way, this is probably the best thing that you can do!
I was just trying to clear up the misunderstanding about distro specific packages and who creates and maintains them since most people don't have much experience with the process.
It's also worth nothing that this isn't really a one way or the other deal, you can provide a portable method and people can package your software eventually. I think the two styles work very well with each other.
This is divorced from reality. You're right, I do not have the experience to package it on every distro. I do however get bug reports that "$app does not work on $distro" that I have to fix as the software developer of $app, because "just wait for another software developer that understands $distro to package it for you" is not an acceptable workaround for users.
Even something that seems innocuous like, "oh sorry it's not available for that by default, here's a tarball" is too much friction for user applications.
Flatpak is the closest to a solution we have, but it has its own issues. It's infinitely superior to "just use the standard build tool like $(N different build tools) and list your dependencies, then pretend it's someone else's problem to solve!"
You most likely don't have experience creating and maintaining packages for every distro that exists, expecting you to be able to do this would be silly. Typically the users or developers of the countless different distros will be who handles packaging your software though, not yourself!
As a developer you just need to provide the source code, use a standardized build system such as make, cmake, meson, cargo, etc, and a list of libraries that your software depends on. If you do these things, creating a distro specific package for your software will be totally trivial for whoever feels like doing it and contributing to their distro's repo. Most distros have decades worth of tooling accumulated to make packaging software that uses standard build systems absolutely trivial!
Optionally, you can provide a flatpak image (or similar) for users who want to circumvent the system package manager.