[WPMU DEV site] Search for comment/thread by user

I'd like to search this site with a filter by user ID.

Have you ever wanted to find a quote by someone here? To my knowledge, the Search box in communities does not include a user=foo style for filtering (and to refer back to prior notes ... the Search in this site is still really bad)

Have you ever wanted to go back and link to something you wrote a long time ago? Our profile page has no search box:
So to find that thing we wrote, we need to go through each page of our posting archive, and manually look at each thread.

In the bigger picture, I'm confused why a simple feature like Search is such a challenge for this site. Why can't we filter by date, by author, by commenter, by subject? I know we can Google search the public content, but that doesn't help to refine down to user IDs, dates, or anything in member content. How about creating a search page, and then progressively add filters? Really, how tough would that be?