Good point, I hadn't thought about it that way. I think you brought that up early on in the Danmachi cross, but I'd completely forgotten about it.
Actually, the way that Taylor doesn't consider non-hosts real people could add an interesting dynamic to the
Highschool DxD crossover I suggested
here. In DxD, while joining a peerage turns you into a devil, most of the pieces were originally humans and still have human values. Even the couple of main devils at the school - Rias and Sona - have human values, and they try to socialize to a level with the humans around them. If Taylor sees devils as host equivalents and therefore actual people, but doesn't consider normal humans to be worth valuing, this could create tensions with others in her peerage.
Something else that occurred to me is that devils make contracts with humans who summon them, since if they fulfill the requests their own power increases. But to QA/Taylor, this could sound like the shard system of giving "gifts" to humans as part of the conflict cycle for research/growth. So when Rias or Sona asks them to do some contracts, they take up the role of a jackass genie who "grants" wishes by giving them powers akin to shards, in a way that will encourage conflict. Rias/Sona would probably stop it as soon as they learned what was going on, but QA/Taylor's misinterpretation of the contracts' purpose would further demonstrate their distorted understanding of things.