I think its the only way to not be completely dependent on some single entity.
So far we have seen all of them go bad with time. At least with federation, you and me can talk with no corporation in the middle, which brings me back to the lovely feeling of the 90’s with BBS’s and forums. Before the corps took over and put ads everywhere, and basically took the world hostage.
If something big happens, ordinary people need to be able to talk without censorship. And its going to be very hard to censor a distributed network like Lemmy.