See a pizza is a form of pie, made with flatbread,tomato,local vegtables, local cheese,and meats. It has been around for 3000+years(Marco polo introduced it to Italy after a trip to China). Pineapple was neither available or even though about when it came to pizza....for thousands of years.
Then in 1962 a Greek who had moved to Canada named Sam Panopoulos thought it would be interesting to try,being the hippie he had become in Canada. Thus a can of pineapple was added to pizza, and force feed to small children who were raised to spread it as a new religion. To this day the descendants of those children spread the false religion of pineapple on pizza, trying to convert ever more humans into their cult. I have no doubt BigMoose and OneBadV8 are direct descendants, at the very least kissing cousins of those original children.
Luckily they are still very much a minority on earth, otherwise all traditions, all values, and all other belief systems would be destroyed.
I will stay strong, and maintain the 3000+ year old traditions of what a quality pizza is and it will never involve a pineapple.