Flatpak and Snap certainly go in the wrong direction, instead of being an upgrade and replacement for existing package managers, they are a crooked sidegrade, that solves some problems, while creating multiple new ones that used to be solved by older package managers. Flatpak making Gnome and KDE the only dependencies to exist is also pretty messed up.

I don't mind AppImages in this, as they never set up to be a new package manager format, but instead are just a way to bundle executables and dependencies into a single file for easier redistribution. You certainly don't want to use that for all your packages, but as a quick&dirty workaround to get some semblance of cross-distribution packaging, with close to zero impact on the user, it's quite good. It's also one of the few formats that gives the user full control over up- and downgrades, as it's all just simple files you can run and archive as you wish, it's not a service that forces you to always use the latest thing.

So yeah, Linux packaging is still a mess and it will probably take another decade or two before the dust has settled. Though I can't shake the feeling that we have reached peak-Linux quite some years ago and it's all downhill from here. Free Software principles aren't exactly high priority for any company doing development in this space, and Free Software principles by itself aren't even enough in a modern SAAS world to begin with.

Somebody needs to write the book on what it means to be Free Software in the modern world, especially when it comes to online-services, distribution and reproducibility, aspects that have been largely ignored so far.