Because people want the status symbol of having a dog without actually liking dogs, so they buy "convenient" dogs based on traits like how little they shed. Then the second they aren't puppies anymore they dump them with a trainer to "train" all the dog out of them and/or dump them at a doggy daycare to torture the minimum wage employees who actually like dogs, all so the owners can take photos for their social media.
Tl;dr: I love all dogs. But poodle mixes are exclusively owned by terrible people, and as a result, act terribly.