Honestly, I think there is a strong case for husbandry being a large contributing factor to the severity of the wobble, particularly husbandry in a young, developing snake. Your husbandry for your rescue may be spot on, but there is a reason it needed to be rescued in the first place. I don't like anecdotal evidence as an argument, but many of the severe wobbles I see shown on the channels of those pushing the ban are rescues. Who knows what conditions they were kept in as they were growing and developing. It's simply common sense that the conditions under which a growing and developing animal are kept have an impact on the outcome of that growth and development, particularly in the case of one with this kind of neurological condition. Environment, particularly that one you grew up in, can absolutely effect the expression of such a condition. We know that to be true in humans.
I do think that there is a possibility that breeding has something to do with it, but most of the knowledgeable breeders who have been breeding spiders for a long time say that it is definitely hard to predict severity of wobble, a parent with an almost nonexistent wobble will produce offspring with a severe one and ivce versa. I think the difference is that responsible breeders will not offer an animal with a wobble that severe for sale.