>they don't harm people since they're not required to try or use them

For users, no. For devs, there absolutely is pressure to support and maintain multiple distribution methods for Linux users.

I don't think that's true. Usually upstream devs and distro maintainers are different people. If I ever see packaging maintained by upstream, it's more often than not just for a single distro (most commonly Flatpak, then Ubuntu).

That's a good point.