If registration are closed, mods would be exclusively from outside. And, since reports are not federated, this communities would be prone to difficulties for moderation. Unless reports are correctly federated, I don’t think this is a good idea.

It wouldn't be that difficult to write a little bot that can keep track of each moderator is on each community, and make the report on the instance of the moderator directly.

centralization of domain names under you.

The idea is to have the domains under the control of this collective.

Can you name any advantage??

• Less concerns about political fights among "user" instances affecting communication among communities
• Less tribalism regarding "what community is the canonical one". Users and admins are of course completely free to create their own communities, but for the majority at large they could just look at the topic-based instance and think "ok, that one will be a good entry point".
• Less load on all servers. LW has a good chunk of the most active communities, so all activity from other users end up going through that. More instances with cleaner separation => better load balancing.
• Easier content discovery: no matter if users go to a small or big instance, they can be pointed to the different servers to browse according to their interests.

hardly anything huge to really break the inertia or status quo of things as they’re now…

As it is right now, yes. But I am working for a potential future where we can migrate 10, 20, 50 times more users than we already have. Consider that I am also working on a tool to help people migrate from Reddit and in making some modifications on the Voyager app to integrate automatic migration from Reddit to Lemmy. If the gates finally open, this will be very much needed.