How does a completely decentralized platform handle data that should be removed? If some asshole starts posting CP or other fucked up shit, what exactly happens? With mastodont the server admin has the control to remove whatever he or she wants. Not perfect, but you have plenty of servers to choose from (or you can start your own).
You want something like society, mostly free but still with some ground rules. If it’s completely free there is also lots of scams and shady stuff. In the long run I think a platform like that will be banned by governments.