I think it's a relatively recent addition as well, so stuff that was big back in the early 00s won't have the flag and be incomplete by default. That means a lot of anime series that were huge back in the day can get in even if it doesn't seem like they should.

I vaguely recall like...Pokemon or Hetalia or something that clearly didn't deserve to be in Yuletide sliding in one year based on that, but I might've hallucinated it.