Several of my DDs friends ONLY got offers from Oxford. Really , four rejections and then a yes from Oxford.
DD herself was rejected from all her uni choices in year 13, including Oxford, bar Durham despite predictions of 4 A grades. Tried again for Oxford post A levels with much the same personal statement and reapplied to the three universities which had rejected her as well(with actual results marginally worse than predicted the year before) and got offers from all three within a week of her application followed by an Oxford offer a couple of months later.
Meanwhile DS applied pre A levels for PPE to Oxford, Warwick, York, Exeter and Durham, got offers from Warwick, Exeter and York ( all within days of being rejected by Oxford). Accepted his 3 A offer from Warwick, in fact achieved 3 As and applied again to exactly the same universities. Offers quickly from York and Exeter then had to wait an age for Oxford interview and rejection ( waves at ponders*), then got offer from Durham...and then just a week ago ( ie 6 months after the application) got a rejection from warwick. the same university who had wanted him the year before and whose offer last year he had out achieved. I suppose it wasn't rocket science for them to work out that he was applying to Oxford, and apparently they didn't like it but clearly they kept him hanging on as an insurance almost until they were sure they had filled all their places.
But he LOVED Durham when he went there just before easter so all is well that ends well.
And to precis above rambling post - I think for the oversubscribed courses it is a kind of lottery and I also think that some universities assume that certain candidates are "too good" for them and are almost certainly headed for other unis and don't want to "waste" an offer on them