Pizza is not really Italian. A lot of cultures have invented flatbread that you top with stuff before baking. It just happens that the Italian version of that got spread around widely. And then other cultures added their own flairs, one of which is pineapple, usually connected with a salty pork product like ham or Canadian bacon.
Here in California, that's called Hawaiian style pizza, and I didn't get it, myself, until I tried it and found it's a pairing that works, usually with extra mozzarella cheese.
I don't know that it's actually Hawaiian even in style, though my wife's family used to like going to Hawaiian-style fast food, which involves a lot of Spam (the Hormell kind), so there... may be a connection?
My parents' generation, in the 1970s way dug anchovies on pizza which I found way too salty. I didn't get it then, but I don't see much in the way of anchovies on pizza now. So collective tastes may change with time.