practically speaking, people creating their own webpages and hoping to get indexed by a search engine or included in a hand-curated directory is not going to get anywhere close to that. you restrict your creators to a tiny, tiny fraction of the population w/ those skills.
so the trick is how to have the great ux of these centralized services without the downsides of centralized control. seems like there's a good chance it's possible.
(for other services, we did used to have (well, still do) pretty good decentralized variants. slack vs irc, reddit/hn vs newsgroups, email vs fb messenger. but even the more minor usability improvements of the centralized alternatives seems to be enough for them to displace what came before. maybe the tide will swing back.)
They're certainly useful. I just question whether we wouldn't have found other ways to achieve these kinds of benefits if we didn't have YouTube, with the entire Internet interested in the results and well over a decade to come up with something.
Ironically, we used to have a nice, decentralized Internet, and services like YouTube have been probably the biggest cause of damage to it.
Not so many years ago, everyone got a bit of web space and their own URL along with the connection from their ISP. You could put your own web site there, for all to see. Many ISPs would allow running some basic software. Visitors would find these sites through search engines or [gasps] manually created links from other sites with relevant material.
An analogous service today would probably involve providing a useful amount of space and bandwidth, and probably some ready-made blogging or video hosting software so non-geeks could just start creating something instead of having to install anything first. But in reality, almost no ISPs (at least here in the UK) routinely offer that sort of service any more, because the likes of YouTube and Medium have killed it.