@briongloid Not admins. Users should be able to do it.
As an admin, there is no way I can be across all of the niche subtleties and naming schemes of communities I'm not involved in. If I have to group them, I'm going to get it wrong.
If it's going to sit anywhere above the individual level, it should be at the community mod level, not the instance admin level. But of course, many community mods aren't going to want to actively point people at other larger communities that overlap with theirs.