Might be a difference between libs and rads again. Lib vegans who do it for vibes won't see a problem with getting Snookles from a breeder because it's the perfect mix of Japanese-French Bull Russell Madagascar Terrier (I don't know dogs). And if you tell them their "perfect little angel" that barks at every black and brown person will die at age seven to heart or liver failure, they will talk shit about you to the HOA or the PTA or whatever.
Rad vegans, depending on how involved/knowledgeable they are about certain issues might make errors, but imo when you bring up these points, they will change their mind and make adjustments. And a lot of them already have in many other ways. That's why, on this issue, most rad people in general, even non-vegans, always want to get pets from shelters instead.
So, yeah. It's a problem because people have divorced veganism from other struggles (and associated it with California quackery like crystals and shit).