>Why? Couldn't I just use the "Get all the replies to your messages" icon? I don't care whether I see the thread listed in the main screen.

As I said, you would loose the ability to get your replies within new messages. Those are two different things.

I think the current layout for defining forum participation is what it should be all about. Members decide in which they want to participate. If you have a need to participate in one for just a few days, then checking it for a short period would do.