But, imo, "fork it yourself" does not invalidate any argument. Thats just going to result in Lemmy, and Lenny, and Lambchop, and Lemmiwinks, and lord knows what else...
as long as you don't change the principal of the federation system it will remain the same, even kbin and mastodon are reachable from here and can put content here, you can change some things like link a own CSS to have a different GUI or make some other things with it.
They would only need to update the code if its a change regarding the federation (votes, posts etc)
The whole idea of this federation business seems to be about freedom of choice and getting away from "them" telling "us" what we can and can't do with our time, our content, our data. And basically my first experience with this platform was seeing the primary dev shutting down multiple issue tickets full of perfectly reasonable arguments because... I dunno, "Nazis are bad and I'm smarter than you, mmmkay", I guess?
As said the handling was bad, but since then it seems to have changed and since the code is open source its 100% possible to fork it and work on it with a new dev team, if its better than the current one its gonna be used by more instances as well.
The altitude seems to have changed a lot since then as well.