Ketchup is a prime example.
Extremely popular yet a culinary travesty.
You remind me of a snobby upscale pizza shop (still a pizza shop in my eyes) that refused to serve me ketchup with fries for the reason you specify. I won’t be returning there.
Everything has its place, including Ketchup. And for the record the fries weren’t that good that they would be ruined by ketchup.