I’ll chime in: simplicity. It’s much easier to keep a few patches that apply to local OS builds: I use Nix, so my Mastodon microVM config just has an extra patch line. If there’s a new Mastodon update, the patch most probably will work for it too.

Yes, I could build my own Docker container, but you can’t easily build it with a patch (for Mastodon specifically, you need to patch js pre-minification). It’s doable, but it’s quite annoying. And then you need to keep track of upstream and update your Dockerfile with new versions.