Honestly, I just think this is another feature which wouldn't benefit the forum too much. If threads are becoming redundant, and encouraging spam you can report them.
Then probably 90% of threads here need to be reported and locked. Even ones that start off well or interesting just get shitted in by one/two liner spammers who don't really understand the topic or even bitcoin. As long as we've got people who are getting paid to post here then they're going to continue creating generic shit threads to have somewhere to crap in. If we're not going to do something about the source of the problem, which is ICO campaigns, then it's futile even trying to do anything about it because you're just trying to patch up a sinking ship. Take out the cause of the problem which is the sig campaigns that are constantly firing shit torpedoes into you instead of trying to futilely plug holes that are never going to solve the issue that is sinking the ship in the first place.