Theory: most dogs never get the chance to act like dogs
I've never really been in the pet dog world so what I see of it on Reddit is absolutely wild. I theorize that most of these dogs never get the chance to act like actual dogs, because they are thought of as being, and treated, like human children instead. So when they do act like a perfectly normal dog, the owners have no idea what to do because they have never seen an actual dog acting like an actual dog either. This is why people are so immediately out of their depth when they get a puppy that has absolutely no training on it and they are responsible for putting the training on. They have no idea what a puppy actually acts like and they expect it to act like a human child and develop mentally like a human child. Most likely all of their friends treat their dogs like human children as well. And then they are even more susceptible to the misinformation from the positive only cult, which reinforces the idea that dogs are like human children. And then they are off and running on the behavior problem cycle and can never get out of it, because they simply don't know what a normal dog acts like.