There has always been a who you know, my son got into the trade because who he knew, me, an employer wanted me, he said what can I offer you to get you back, and I said job for my son.
Also the all other things being equal then looking at anything from leisure activities to schools attended. I got my first job over a talk about chess.
But you can't say any children have an advantage or disadvantage if no exams taken and as a result no exam results, only when you fudge up some results is there a problem.
The problem today revolves around the league tables, before them I could walk into a collage and sit any exam I wanted, it did not matter if I passed or failed, but the league tables resulted in no external candidates as it could bring down their rating, so you had to take the course and be recommended to take exam by the teaching staff to be able to have a stab at the exam.
As long as that is removed then any students can return to school or collage to take the exam. And they will need to, as employers are not daft, they will in the future ignore any 2020 exam results as they all know there was no exams, so a 2020 'A' level will become worthless.
There is really no option, they need to be given a chance to sit the exam. The problem will be how well did they learn during lock down? Some will have been taught by parents also on lock down and it will depend on parents skill, so some will have learnt more, and some will have seen it as a holiday. So the actual results will not be as predicted as no teacher can predict how good the parent is.
There is also the fact that 'A' level books are not always correct, I did 'A' level physics about 4 years ago, if I did three subjects it was £10 if not £80 per subject, so I did physics as thought I would know most of it, but the circuit diagram for a fluorescent light completely missed out the ballast, so had there been a question on it, I would likely have given a different answer to most students.
This of course happens in all walks of life, as an electrician the question what should you do if you find a damaged tool will be different to an ordinary persons answer.