not surprising. centralized communication platforms suffer from the hug of death naturally occurring when people want to read information all at once.
Maybe it's bad when lots of people want to interact with information all at once.
Or maybe when access to information is gated behind a bunch of javascript client/server interactions.
On the other hand, I'm out of touch and still just write static HTML pages when I can get away with it :þ
That's what PeerTube is good at. Each video has a home site and a master copy, and each watcher helps to redistribute the video. So, if your cat video goes viral, your tiny server doesn't get hugged to death. At least in theory.
This is less distributed than bittorrent or Usenet. It's just distributed caching. Only videos currently being watched are replicated.
Now, PeerTube doesn't help with discovery. PeerTube sites only list their own videos. For this to take off and replace YouTube, a discovery mechanism (what we used to call a "search engine") is needed. Those exist.[1] (There are others, but some have bad SSL cert warnings.)
If you break the problem into discovery, hosting, and caching, all three parts are tractable. And no one part has enough authority to get uppity and act like they're in charge.
I'm just stating the obvious, which is that whether a service is centralized or federated has nothing to do with it. Mastodon would melt long before operating at Twitter scale, for example. (And to your points, I don't think that's necessarily bad.)
But, if there's any company on earth that should have 20/20 hindsight about this, it's Twitter. Post-"fail whale" era and pre-Musk, the service weathered far larger challenges without collapsing.
E.g. signups have hit ~6x what they were earlier today but it's still only an average of one signup per instance per hour.