Well, a huge caveat to that is that there are world class Researchers who create constantly adapting intelligent spam filters to keep spam out of inboxes. Maybe the fediverse will have something like that someday! Who knows!
If anyone is curious about the history like I was, the Wikipedia article is quite well done:
Web 1: Decentralized everything
Web 2: Centralized everything
Web 3: Decentralized everything?
Hmm, those are some good points. I am mainly concerned with the difficulty in moderating the server well (especially as it scales) but your and the other comments have mostly convinced me.