I’m not thinking necessarily about moderating or about “power user stuff”.
I may be viewing one forum when something I read triggers a memory of another post I want to look at again. If I happen to know that post is in the same forum, then having the search results favour that forum is OK. If I happen to know the post is not in that forum, then to stop the results showing a bias, I need to leave that forum (and the thread I’m reading) to get an unweighted search.
Disruptive and not very convenient.