The "distributed" part is still to pinned down anyway (which architecture scales and which not, under what definition of "scaling"). The discussions between activitypub and atproto protocol folks are informative in this respect.

But there is another non-trivial difference: these are open source projects.

The real Achilles heel is having a viable business model. But all business models, whether good or bad are inventions. Unless we think predatory adtech is the end of human ingenuity people will come up with ways.