It's also not new; lots of it is new branding on an old concept. HN has long had karma points and a karma leaderboard, if just that is enough to count. Forum software since at least the 90s has had "levels" for posters depending on how long they've been there, how much they've posted, and on a few forums some attempt to measure of the quality of their postings. Even the old Experts Exchange had a "gamified" question-answering setup, with a system of points, levels, and features.

There was another big wave of it a few years ago when "crowdsourcing" became a big buzzword for a while, and people were designing game-like mechanics around that.