

I’m not sure that would work. Admins need to manage their instance users, yes, but they also need to look out for the posts and comments in the communities hosted on their instance, and be one level of appeal above the mods of those communities. Including the ability to actually delete content hosted in those communities, or cached media on their own servers, in response to legal obligations.
Thread is a bit more power efficient, which matters for battery powered devices that aren’t connected to permanent power and don’t need to transmit significant data, like door locks, temperature/humidity sensors, things like that. A full wifi networking chip would consume a lot more power for an always-on device.