We all know Carlsen is the actual world champion, yes ? He's still the top rated player. He just didnt feel like doing it again.
There is a difference between being the BEST player in the world. And being the Classical Chess World Champion. Thats like saying when Hikaru beat Magnus in the Blitz World Championship, that just because Magnus was "higher rated" he was actually the best blitz player, it doesn't work like that.
No, I was just talking FIFA rankings.
But the same thing goes for anything else - Snooker, Rugby, Darts, Cricket, Athletics, etc...
They all have World Championships and it's not necessarily going to be the top ranked players / teams who become the World Champions.
But that's okay because winning a World Championship competition is not the same as being rated World Number 1.