Not only does pineapple belong on pizza, ham & pineapple pizza is the only pizza that is consistent in all three states: fresh and hot, cold, and reheated.
I despise when people are food traditionalists. If we listened to them, we'd still be eating like British people.
I grew up in El Salvador listening to people insist that only beans, cheese and pork go in pupusas. Otherwise it's a sin! Well the young people now make them with everything you can think of from shrimp to sweet potato and it's incredible.
You don't like pineapple on pizza don't eat it
To add my personal opinion. New York/North American pizza is better than Italian pizza
The reason why it's good when reheated is the moisture in the pineapple. It keeps the dough from becoming a rock formation when reheating.
For non-pineapple pizza, adding a bowl of water into the microwave has the same effect.
That said, the argument is not whether pineapple is good on pizza or not, ofc it is, everything is good on pizza. But is it the best topping? No, that's anchovies and capers (olives are good too).