love the spirit, but very incorrect, on multiple counts.
they do not all cut corners. just because you have experience with backyard breeders does not mean all dog breeders are this way. i have known many wonderful folk in the AKC breeder world; people who sell to pet stores are backyard breeders, you will not find a well bred and papered dog in a pet store. good breeders, as a whole, do not let their dogs end up in shelters at all. a lot have contracts that specifically state to return the dog to the breeder if you can no longer take care of them. and it's true that some are terrible and just in it for the money (which in dog breeding means you DO have to cut corners, because the profit is pretty slim to begin with), just like literally any other job that exists. you've probably known vet professionals who didn't deserve their jobs either, and i have too. i'm not out here saying TREAT YOUR DOG AT HOME! DIY, NO VET! these comparisons are not exactly identical, but it seems foolish to condemn people who are committed to bettering their breeds and producing dogs who will be healthy and happy wherever they end up. who aren't doing it for the money, because the money isn't good. they just love the breed they work to improve. a great example is the movement growing behind breeders of brachycephalic breeds, working to move them away from the terribly squashed face that gives them a slew of health issues. there are breeders that give a shit. there are a lot of breeders that give a shit.
people who buy dogs from good breeders are doing it for a reason. either they want that specific breed (which could be resolved by going to a breed rescue), or they want a specific temperament, lineage, confirmed health history, etc. which cannot be resolved by adopting. these people are never going to go to a shelter. these are not people who just want a dog, any dog will do. "adopt don't shop" works for people who DO just want a dog, any dog will do, and would probably buy their dog off craigslist or go to a pet store. but most people need a specific dog that works for their life and their situation, because all dogs are different just like people are, and you cannot always confirm that with a shelter (and are often lied to about the history and temperament of the animal to begin with, in a shelter situation. i have plenty of horror stories about that, too). some people would rather not have to deal with bringing a dog home and finding out it's a poor fit for their home. at the end of the day, there is not a world that exists where breeders don't. you cannot get rid of this unless you can fill the very specific niche that breeding fills, which you cannot do.
large male dogs should be neutered, but we have seen in studies that they probably shouldn't when they're at the age that dogs usually get neutered, because it is better for their health (if they are not showing behavioral problems as a result of being intact). this is neither here nor there when it comes to the breeder vs adopt debate, i only mention it because you highlighted it very specifically. also, holy shit you are so right about the weird way people feel about neutering their animals...you'd think you told them to cut their own balls off, the way they act sometimes.
in short: breeders have a purpose. adoption has a purpose. good breeders are not contributing to overpopulation because generally speaking, their dogs do not end up in shelters, they do not end up in companion homes while intact, and the people who get them were not going to adopt to begin with. the problem with pet overpopulation is not just that breeders exist, and eliminating breeders as a whole will not fix it. eliminating backyard breeders certainly would. but i think you are conflating the two, and condemning the entirety as a result, without considering the actual nuance behind how these decisions are made and why.