Why, in online chess, is it that the shorter the time control, the higher the world leading elo is? I noticed on lichess.org that the shorter the time control, the higher the world-leading elo is. Is there a simple explanation for that?

I also noticed that, in the meantime, the shorter the time control, the lower the median is vof all players. I think it is because, the shorter the game is, the more you need to know by heart many openings and the more you need to be skilled to be good at such mode.
I think the key of this is number of played games.
Nihalsarin2004 9440 bullet games
konevlad 1113 blitz games
Zhigalko_Sergei 257 rapid games
Biranidun  84 clasic games