I think communities having a pinned link to a different community would see the exact same purpose as this but without the extra dev time

I like the idea, but i'd prefer an almost sub-sub-community approach (especially without having any form of tagging implemented).

like if a specific topic becomes too frequent, you could use the "mega" or "super" thread pin slot to instead give a new view of all threads of just that topic, sortable and searchable the same way a regular magazine or community is.

This clears the main feed for the community, doesn't stifle discussion as they are still their own posts, and really has all the benefits of creating a whole new community just for the topic, but while keeping the current moderators and community in control. A nice intermediate step between "this topic is flooding the community" and "this topic demands it's own community entirely"

Bonus: each metathread (which i'm calling this idea now, i've just decided) serves as a automatic archive of the event/topic in question.

Could even come with a "promote to full community" button for moderators who don't want to deal with it anymore.