I still see tag videos from small youtubers and vloggers in the various groups I am in. I've also seen a video by Brian G. Johnson where he talks about the 'new youtuber tag' as a way of getting yourself out there, so apparently it must still be a thing and people actually do searches for that stuff.
To me though, it seems that this has somewhat left YouTube and crossed over to Facebook, just not in video form. But when you see those chain-mail posts where you are supposed to answer all the questions, and then encourage your friends to copy and paste your post as their own post and answer the questions also... well, that's the equivalent of a YouTube tag video, lol.