It’s definitely a useful feature. I’m still hoping that this is eventually added to Lemmy natively, as it would be more efficient, and accessible for more users. It makes for a good alternative to following topics such as on mastodon.
It sounds like I should probably find a way to make this feature more apparent though. As it is right now, the UI doesn’t really express that this feature is available unless you’ve already created a community group.
One tweak I would do is to the way we add communities to a group. Often many communities have the same word in it. Let’s say I want to add all the ones with Arduino in it, I should be able to select all the ones I want (with a checkbox) after searching for that word instead of having to add them one by one and type Arduino in the search every time.
As to make it more appearance, maybe have the multi-community section always visible in the community list.
Edit; also, having a button that says Addto Multi-Connunity in each community menu (next to favorite and block) would be a nice way to use this.