Most normies dont want to set up their own mail server, they just want to log into a "service" that allows them to send/recv mail. Thats how companies insert themselves into peoples lives, as a low friction and often free way to save time and effort (free but you're still the product). How are protocols going to solve that problem? Someone will still have to donate their time and effort to making other peoples lives easier and then you have centralization again. Unless a service is distributed by default I can't see any technical solution.
To me, this is what it ultimately comes down to. It is a normie world: sure, they care now about the ID and face scans, but the reason it even got to this stage is because everybody wants to be on the platform that everyone else is on, and the platform that has the most eye-catching features is the one that gets picked. Not the one with the most robust protocol that prevents centralization but can’t save a chat history, get channels renamed, or has no voice support.