Gmail and Yahoo will do retroactive classification to some extent, but not broadly. It's a little more common to defer delivery by varying amounts based on historical sender reputation, but again that impacts a minority of legitimate email - maybe 10-20%-ish, off the top of my head - and mostly only by a few minutes.

And yes, every major consumer email provider tracks complaint and response rate metrics (as well as many other metrics and indicators) and uses those as part of their filtering. A spam ratio of > 2% is often enough to cause filtering - that's actually toward the very top end of the complaint rate spectrum for messages that are delivered to the inbox.