To follow on from @tmattio’s comments, I also raised the same query during the design process. As far as I can figure, most modern websites are designed for mobile usage – a huge percentage of users now come in via tablet/mobiles, and so responsive design is really important. That explains the medium/small layouts, but not why there is so much whitespace in the wider screen layouts. It’s really obvious when comparing an opam.ocaml.org package description with the equivalent on ocaml.org/p. The next iteration of design is beginning now, so please do help out with the survey and your thoughts that @sabine just posted about, and we can get those fixed.
The problem is pretty simple: PeerTube doesn’t support shared video channels, so one user has to own them. In our case, the intrepid bactrian returns for all the OCaml Workshop videos.
If we do create separate users, then it also looks weird. For example, @patricoferris uploaded OCaml Workshop 2022 videos under his own account, and now when you reference them from Mastodon it looks like you’re referring to @patrickferris since it drops the domain portion by default. See here for a ‘toot’ that is owned by the bot, and here one that is harder to distinguish.
And then… I did indeed create you an oups@watch.ocaml.org account in April, but you haven’t uploaded anything since. What do we do if someone else in the future wants to take over OUPS videos and get them online? You need to account share. Most of the ActivityPub services like Mastodon and PeerTube are quite user-centric at the moment, and not well suited to shared publishing. But it works well enough with a little coordination amongst ourselves and some trust. Concrete suggestions for improvement welcome.
Even better with issues to improve the ocaml.org website 
Now at ocaml/ocaml.org#767 and ocaml/ocaml.org#768 for your events suggestion.
Using decentralisation has got nothing to do with one hosted instance. By using these protocols, the information related to OCaml can be replicated across multiple sites and reconstructed if one service goes down. For example, my personal crank.recoil.org instance “follows” and mirrors the videos on watch.ocaml.org, as do around 50 other PeerTube instances. So the ocaml.org domain is most valuable as a namespace, where it can aggregate and publish information that is actually generated elsewhere. In an ideal world, the ACM SIGPLAN team would publish their videos on PeerTube as well as YouTube, and ocaml.org would be a bookmarking/mirroring service.
While this is the theory, in practise the ActivityPub protocol is very URL-centric and so makes it hard to recover from federated domains disappearing. You can read more about this in an excellent undergraduate project last year by Gediminas Lelešius on Improving the Resilience of ActivityPub Services.
As for your point about hosting being centralised; I’m not the only maintainer. There are around a dozen maintainers spread across the ocurrent and opam/dune/ocaml orgs that keep everything ticking along. Some of the core machines do indeed only have a couple of people with access, but this is for obvious security reasons. No service has only 1 person with access, so we have a reasonable “bus factor”.
As @jbeckford observed in another thread, we are in definite need of more maintainers throughout the OCaml ecosystem. For infrastructure, the best way to get involved is by help to scope out technologies (like Mobilizon or SourceHut, in this thread), or by contributing to the software stacks behind it (like the various CIs listed in the ocurrent site). My personal hope is that someone will start building complete ActivityPub bindings in OCaml so we can start having some Fediverse fun in our own language 