Like I said, I'm all for Signal becoming federated. It's why I dropped that link to the airdrop feature request. I'd also be in favor of people running their own servers. I mean the server code is available, you just can't connect it with the main network. So as far as I see it, there's nothing stopping this from happening. I see a lot of people complaining but I'm not aware of any major roadblocks. That doesn't mean there aren't any, but I'm just not aware of any. And fwiw, there are alternative Signal clients like Molly[0]. So at least the app can be disjoint from the official ecosystem.
B) Network effects drive the value of tools that are networked. The forks aren't popular at all.
C) Signal is well funded and not in financial trouble, so they can sustain effort on development and infrastructure.
D) I suspect you already knew all this too. So why did you respond the way you did?
An analogy is the U.S. is a two-party system, but most would consider this significantly different than the one-party system in North Korea or Russia.
A federated system with a few large players is still much better than a centralized one.