Yeah I get the aesthetic appeal and all that, but I actually want their in depth reasoning behind it. I mean, among the Blood Supremacists are genuine academics, in fact they’re entire in world books written on the topic. It’ll be fascinating, to say the least, if Rowling (or whoever else invested in the material) were to actually write and publish one of these books as if they were from in world authors.
Looking at the lore it has to be convincing, or at least suitably convincing, stuff because apparently during the time of the House Founders animosity between purebloods and muggle-born was a rarity. In fact Salazar was considered an odd ball for hating them at the time. So I ask what changed? Even before Voldemort casual distrust, and even open disdain, towards muggleborn became so popular that roughly half of Wizarding Britain at least passively ascribe to it. Even in the 90s after a bloody Civil War Lucious Malfoy, who at the time distanced himself from Voldemort, felt free enough espouse blood purity publicly. That shows, at least on the face of it, that even in the 90s it was at least normal enough to be a blood purist so long as you are not, or at least pretend to be not, a follower of the Dark Lord. If that’s the case, that implies too that they’re pure blood Supremacists that were, unlike Malfoy, genuinely against Voldemort. Frankly there is just a whole lot that can be explored with that.