Yep wordfactory I agree it's in no-one's interest to get students who can't cope.
So I would not argue for "sympathy offers" to be made to people who are missing great chunks of necessary presentation that seem impractical to make up, just because their school is rubbish.
But I don't think that the admissions people make such offers in practice - why would they?
The truth is that almost every offer is a calculated risk (unless you have someone obviously exceptional, but truly exceptional people are rare).
After all there is more than one way of not coping - for a demanding course you need a combination of preparation and ability/interest. You can make up a certain amount of missing preparation but no amount of tuition can compensate on the ability front.
Take maths, which has a fairly definite filter - there comes a point (unless you're Alexander Grothendieck) where things just Get Too Hard and people have to drop out if they hit their personal filter point. For some it's O-level, some it's A-level, some it's halfway through their degree.
All the degree-level maths faders I saw had excellent A-level results.
But I'm not saying that universities should ignore A-levels and general preparation levels. It's just that some on this thread (not you) seem to have the idea that taking other considerations than A-level grades into account is somehow intrinsically inappropriate or unfair, and I don't get why.