as someone who tends to enjoy food combos with clashing flavors/textures that wouldn't work in theory but really does work in practice, I think I can understand how and why someone might like it. it adds a certain interesting texture, and the sweetness probably really complements the seasoned sauce/meat/etc in a satisfying way.
with that, though, I have to stress that I really don't like pineapple. I never have, and I probably never will. so as much as I want to say yes I do like pineapple on pizza, I definitely don't. no shade to those who do enjoy it though, more power to you!