@cantkeepawayforever
In the days of EE offers, there were separate Oxbridge entrance exams (one paper in each subject, IIRC, 3 hours each), as well as interviews.
If you didn't do the entrance papers, then offers were conditional (and high - including S levels).
By comparison, the colleges just don't have the same level of information about this year's candidates.
I think the point is though that the A Level grades will also not give very much information, or at least, not much RELIABLE information; they may only reflect how much each student has been able to be in school.
Dd would rather do the exams too, but in any sort of race or ranking, it is so important to ensure that everyone has a fair shot - and that is just not the case. There are schools I know where in some subjects Y13s are not in more than 50% and even then aren't in subject specific rooms - subjects like art/science/music are bound to suffer - and you have to remember that the way grade boundaries work is that proportions, however they are drawn, are fixed, and will benefit most the students who have had least disruption.
To put it simply - if you were offering places based on how fast each student could run 100m, and you discovered the stopwatches were all faulty, you wouldn't continue to offer places based on those unreliable times...