I wouldn't say they are the opposite, they are still federated with a lots of instance, just not LW and SJW.
About the grouping of communities, that would be an improvement, but at the same time, wouldn't that be strange for new joiners to have to group a few communities on the same topic while they only want to follow it?
I know it's a balance between centralization and decentralization, but sometimes I feel we went a step too far in the latter.
For instance, if !databreaches became the one reference community on data breaches, that would be nice, we probably don't need a community on this topic on 4 other instances