It didn't kill forums. They survived. But it's a good idea to archive them. There are a couple of forums that have been down for 20 years, and I read the archives. The discussion quality is better than anything on reddit. 

Search is not that big of a barrier of entry. Biggest one is prerequisite knowledge. Even if you find good info, you can't make use of it without related experience. E.g. a forum for film photography will confuse most people without knowing the techniques. So most people will stay away from the forum. The notion that half the world will be brought to that level of awareness in any advanced subject is completely ludicrous. Discord doesn't solve anything (unless you count talking to lolis as a problem)