A bit more adventurous … I’m wondering if “community only” and “user only” instances might make sense at all?
I suggested this in another thread. However I've come to see an issue with that idea. The users.
It's very hard to change the URL of an instance for federation purposes. All the existing posts and comments that exist everywhere will reference the original URLs.
My suggestion was to move the user side to a new URL. But, the problem there is that lemmy.world is one of the main instances that are suggested to potential fediverse denizens. I suppose the user based URLs could redirect to a new lemmy user only instance keeping the original federating.
It would make some difference in terms of load because the one central point both federation and user activity is going to hit is the SQL server. The user side would be just one more instance pulling data from the federating site. And all user activity would hit the new dedicated DB. There's still going to be an upper limit without moving toward clustered SQL servers and the like.
I think there's a real problem with advertising the fediverse on places like reddit. Because, in one post you'll never properly explain the fediverse. It's a bit like the Matrix. You need to see it for yourself. As such, what would seem like the sensible thing to do (point people to fedidb or the observer one) will likely confuse people initially. Pointing them to lemmy.world or kbin.social makes sense for this reason, get engaged and understand later. So, I'm not sure how the long term solution to this goes.