Nonsense. Even the servers of The Dear Leader of Mastodon would not be capable to process all the traffic between the accounts of various instances.

Each instance would create such a vast number of Sidekiq jobs that individual people would run out of their hosting plans for individually run instances immediately. Larger instances would need to scale even more thereby making the costs sky-rocketting for the site admin. And who would reimburse them for these expenses? Ads? Big Tech? (For tech details: https://ar.al/2022/11/09/is-the-fediverse-about-to-get-fryed-or-why-every-toot-is-also-a-potential-denial-of-service-attack/)

The #fediverse, by design, cannot provide a Social Media haven for many people. #Federation as it is implemented today with ActivityPub, relies on small instances with few users and little traffic in order for the copying-process of posts not to create high costs, to be paid by the site-owners. Alternatively, one may have a federation of a few big instances. But how would that be different form the silo of X-world?