You can simplify everything down to a few repetitious tasks.
"Seriously - how many [FPSes] are just the same [game] over and over again with different graphics? ...but by [the time you've killed something] you've pretty much seen all of the gameplay there is to see."
"Seriously - how many [versions of Solitaire] are just the same [game] over and over again with different graphics? ...but by [the time you've put one card on top of another] you've pretty much seen all the gameplay there is to see."
"Seriously - how [much porn is] just the same [thing] over and over again with different graphics? ...but by [the time you've seen one pair of boobs] you've pretty much seen all the gameplay there is to see."
Ultimately, you can simplify all of human experience down to repetition if you want. The definition of gameplay and fun differs by person. Even though WoW doesn't fit your narrow definition of fun, it seems to work for a lot of people. Look at the Penny Arcade comic you linked--sure, it pokes fun at the expansion, but I think Gabe is still pretty heavily involved in the game.