I mean, to my understanding, those domestic foxes, while tame, are still not quite so perfect of pets as animals that have been bred for longer like dogs are. Though there is no reason it can’t be both, while a dog raised to be aggressive will probably be aggressive, and one raised well should be far less likely to be, it’s not fair to say that there is no genetic basis for friendliness and aggression, else there would be no need for domestication in the first place. A lot of selective breeding can be done in century, so the past few centuries of what an animal has been selectively bred for probably matter a bit more than the centuries before that, to a point anyway. I doubt anyone is really arguing that pit bulls are irreparably damaged as a whole either, but if an animal has been bred for aggression for awhile, undoing that is going to require breeding for the reverse, or crossbreeding with another line that does not have that trait and selecting offspring that do not display it, or similar.

I’m not really sure what stance to take on pitbulls and similar breeds myself, I’ve known some people with rather nice ones and it seems to me that any law targeting a specific dog breed is going to be somewhat impractical given that breeds are “fuzzy” categories with ill defined edges, not clear and sharply defined, so determining what animals are close to pitbulls but are not quite, and which are considered to be pitbulls, but barely, is going to be a very difficult line to reliably draw.