The hate comes from the negatives from pineapple on pizza:
Bottom of crust can be compromised by the wet fruit, making the pie soggy
Pineapple throws off the pizza's balance of flavors
is that pineapple on pizza? it doesn't belong on pizza because it can compromise the balance of flavors on the pie, and can make the bottom of the crust soggy. It's a great way to get a bounty on your head by the Italian Mafia.