As @ls is saying on the thread fork, the choice was made to support the Mastodon API. If you see it in that light, then adhering to the quirks and pace set by #Mastodon seems like the logical consequence of that choice.
Alternatively you might say, we no longer do that, take Mastodon API as a starting point, and develop a Fediverse API that can facilitate all the ways where apps match as well as where they diverge. Then it is Mastodon's choice if they will follow that.