Contextual offers are just that -- contextual. Cite your sources if you're claiming all independent schools get one tariff and all state schools get another, because AFAIK that's not how these contextual offers work.

Oxford admissions have a heavy interview component: if they think you're really smart, have great potential, and then you'll be of the caliber to get 4 A* no question if you had rich parents and went to a top Public School (but don't, so may not), then -- yeah -- they can make you a lower offer. Their place, their rules.

It isn't dumbing down or taking worse students, it's easing out the rich types who will drink/play lacrosse or rugby/bore to at least Blues standard, are pretty bright but have been spoon-fed to get there so will turn out to be dumber and worse students that people whose potential hadn't been fully revealed by 17/18, even if the spoon-fed cohort get better A Level results.