Ehh, people have played games competitively since the dawn of mankind. Chess, Go, Mancala-games just to mention some very well known examples.
Nobody stops you playing for "fun and immersion", but people who play to win and be competitive have fun doing that.
Don't think that your way to play is the only way to have fun in a game, WoW included.
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Do you have any data that confirms your theory?