A bit paradoxal but it looks that all central platform (twitter, reddit, facebook…) are helping the spread of Fediverse. Recently we saw the impact with Twitter on Mastodon, myself I’ve discovered Lemmy even if I wasn’t a reddit user. And before that Facebook first spread friendica and diaspora. It looks next step will be around Youtube where Google try to lock more and more its user.
Peertube take care of bandwidth issue by adding a peer to peer streaming. I don’t know if big instances are having real bandwidth issue. I think Peertube or Owncast issue is more about the money / viewers locking of Youtube / Twitch.