Because those of us on the forums really overestimate the skill of the average gamer.
Just by posting here that makes us all hardcore WoW players. 90% of the player base never even visits any forum or Discord or even watches any videos on the game. They never look up guides or read patch notes or anything like that. They just want to log in for an hour or two after work and kill stuff.
And it’s not just Blitz or even just WoW, you’ll still get “bad” players at even high ranks across most games.