Why? I know that they sell those things but I think it's just marketing. Dogs go around all day sniffing the ground. People try to give them human problems they don't have.
I just found another sturdier, deeper and heavier one, a " slow feeder dog bowls white " from a brand named PETDURO on Amazon ( Amazon's Choice ). It slows down my golden's eating very effectively.
Good question, to get an accurate answer I’ll switch the dogs on which bowls they use, Lexi tends to only use the purple and bear the orange, bear takes longer to eat in general.