I think that we need to talk about the history of software and social software here, because the current status is kind of crazy:
So basically most fediverse is not emulating existing platforms, but trying to go back to an internet we had before the big platforms took everything over. And with ActivityPub we have the protocol to ease some of the pains that the decentralized internet before the web 2.0 era had. F.e. you had to create an account for each individual webforum, which really sucked if you just wanted to ask a question or share something. Reddit with its one login totally took over, because you could participate in many subforums. It was easier to just hop into /r/cooking to ask a question about your lasagna then to find the relevant lasagna forum and register there.
It’s not just about upgrading. It’s also about being able to repair your computer. RAM likes to go bad and on a normal PC, you can replace it easily. Buy a cheap stick, take out the old RAM, put in the new one and you’ll have a working computer again. Quick & easy and even your grandpa is able to run Memtest and do a quick switch. But if you solder down everything, the whole PC becomes electronic waste as most people won’t be able to solder RAM.