When I joined bitcointalk in 2015, I don't remember there being any of those airdrops. That seems to be a somewhat recent development, and one in which a lot of 3rd world country shitposters participate. And, on top of that, I very strongly suspect people are using a ton of alt accounts and that some of those accounts are created for the sole purpose of bumping the airdrop threads. That whole section is just a mess, and I would hate to have mprep's job of moderating it.
Then some of it I think is just people becoming interested in bitcoin because of its crazy-ass rise to $7000. I'm sure that accounts for some of this, but I think it's mostly that damn altcoin token section.