Linux needed a universal package manager and it got three. Snap is not needed.
A bit of history. The first universal packaging format was snap by Canonical and used to be called Click apps and it was made for the Ubuntu mobile OS and later to the Ubuntu desktop. Red Hat in response to that created the FlatPak format. The AppImages are community effort.
AppImages long predate Snaps, but yes, Snaps do predate Flatpaks by a few months. There’s also Nix packages, which predate all three. Of course, this all matters very little compared to the merits of all four technologies. The heavy dependence on proprietary technology for repositories makes Snap clearly unsuitable to become the universal Linux package format.
almost every time Ubuntu goes off and does its own thing, not including the rest of the Linux community in its decisions, it ends up designing stuff that never gets adopted
This is something I like about Debian… They don’t make changes unless it’s really necessary. I run it on all my servers, except an Unraid server. Network config is still in /etc/network/interfaces
in the same format it was in 20 years ago. When they adopted systemd, they still had full backwards compatibility with SysV init, and even today I think you can still uninstall systemd. It just keeps working.