My theory is that the backlash is largely due to implementation problems. The pineapple chunks need to be small, without that tough part of the pineapple and they should be paired with a contrasting strong flavor like spicy or savory. A lot of pizza places don't bother with either - chunks too big, paired with sad ham. I think a lot of these people haven't had good pizza with pineapple, or it's been so long they forgot, and that's just an injustice against humanity.

That's an oddly specific and nuanced set of facts to know about various people. Are they confessing this to you, and if so is it spontaneous or under your examination? Or, are you reading this into their psyches from a distance? Or, are you making these observations about people at different parts of their lives before and after their respective inflection points regarding when they personally come to realize hating pineapple on pizza is popular?

Personally I have hated it as long as I can remember (over 20 years), especially since many Finnish microwave/oven ham "pizzas" often contained pineapple that I had to pick out manually (and still had to deal with the leftover juices).

What kind of commitment is he testing? I'm not entirely sure that the GP is overly inciting anything...