WHY do people get SO DEFENSIVE about new approaches to an age-old tradition?
I might be missing something, but I don't see that as particularly defensive. The fact that you wrote SO DEFENSIVE in CAPITAL LETTERS suggests that you, too, were getting a little defensive.
I actually agree with the poster to some extent. Not everything vegan is good for soil, and not everything good for soil is vegan.
I don't think there's anything particularly new to it, other than the fact that it has a name. "Veganic" growing is, in my opinion, a rebranding (for want of a better word) of "not putting animal matter in your compost". Prior to industrially produced fertilisers etc, most people would not put animal products into their soil because they would be used, partly because this attracts rats and foxes. In Victorian England, for example, bones would be used to make stock, then given to the dog, then
sold to the rag-and-bone man.
Manure is a waste-product (literally and figuratively) associated with riding schools (round here, certainly). I, again, don't see anything wrong with that.