Not all Signal alternatives store user information on servers. Threema for example has fully decentralized groups and even decentralized profiles (while Signal uses encrypted-but-centralized profiles, and their new Private Groups system moved from decentralized to encrypted-but-centralized as well).
There's no reason to caricature anyone's arguments here. Why the antagonism?
So the logic you're using here is essentially: "since we have to take Signal's word for some part of this, we might as well use services that promise the exact opposite". I don't find that argument persuasive, but you do you.