while i generally don't eat it you can put high quality pineapple on a great pizza and it'll taste amazing.
ketchup on steak is basically in the case you have extremely cheap meat which may be bad so has to be overcooked (well done) to prevent getting sick, and ketchup adds some flavor to flavorless, burnt meat. so yeah, easy choice, pineapple every time.
what would be REALLY bad is shitty $1 frozen pizza made with ketchup instead of tomato sauce, well done steak instead of pepperoni, and then pineapple on top of it