I can't wait for #Mastodon and the #Fediverse at large to have #groups integrated and interoperable with each other.
It feels like we're getting close.
The ability for anyone to be able to easily create / admin a group, have it show up in searches as a group, and to block groups will do a great deal for helping people find their communities, find like minded people when they first join and provide support to minorities. Of course it provides moderation challenges, too, but is still a plus imo.
FWIW the #ActivityPub protocol seems to embrace things like groups, specifically saying that an entity in the system doesn't have to be an individual. So the underlying technology is already ready for groups.
I'd say the bigger issue is one of UI, how to display groups in a way that users will understand that they're engaging with a group, and how to avoid things like the notorious accidental reply-all in email.
That's a tricky problem to solve, so I hope it's solved sooner rather than later, then clients can move forward implementing the functionality in a better way.
I think that might be regarded as a feature :)
Or, at least, it was left as a higher layer of the system, with AP just concerning itself with moving content around.
It's the same as AP not specifying how one gets an account on Mastodon or how hashtags or display algorithms are to function.
On the up side, like I said above I haven't seen a really good solution to the UI issues if integrating groups here, so at least AP didn't standardize on a bad solution.