Remember too, that you can't place too much emphasis on Mocks. Different schools sit them at different times, include different elements of the course and some purposely mark them harshly or generously, depending on what the exact purpose of them is in their school. So a L8 in a Jan mock this year, doesn't necessarily mean there will be a L8 in the summer.
It is right that teachers have to take a holistic view based on a wide range of evidence from across the course. It would be wrong to base it on one piece of evidence which isn't common to all schools. It is also right that students and parents and schools cannot know with certainty what the outcomes in the summer will be now. Parents on this thread would like to walk away with a formula to know exactly what their child will be awarded in the summer - but they won't know that info until the summer, in the same way they wouldn't have known it if exams were to be sat. When exams are sat, then later decisions are made about grade boundaries and considerations given to the ability level of the overall macro year group etc. The same will be done this year, filtered down to the school wide level in lieu of exams.
Will results be more 'inaccurate' this year? Probably not I'd say. However, people will think they are more inaccurate. Lots of A Level students won't get their UCAS predicted grades and decide that means the grades they are awarded are unfair because they were going to pull it out of the bag for the exam. But remember that UCAS predictions are very generously inflated and 75% of grades are below these. Students see this every summer, but this summer will just think the system has cheated them a bit......as will the parents, who were also convinced that the big effort that was about to start woukd have significantly boosted the marks. And then there is the unreliable marking of exams. We all know how many are put in for remarks and how many are changed, but also that those from disadvantaged backgrounds lose out here because they can't afford to pay for remarks or do t challenge automatically as many fee paying schools do.
This year, for the vast majority of students (and lots of people will probably decide they are in the small minority) their results will be more whatbis expected and less surprising this year. Instead of the outcome being based on 1 or 2 days and whether a paper suited them or not, it will reflect their overall performance. That doesn't mean performance in 1 mock that they didn't know would count, or 1 essay that unknowingly turned out to be vital, but across all the work they have done for over 18 months. That's a a dream for many students. There's scope for a weak essay or weak mock and if performance has overall been very good, then the result will be too. Schools know that between now and exams, students try hard (most of them) and boost their grades, if not to the UCAS level, to much closer to it.....and they will consider that too. REmember the grade teachers give won't be on 20 March or on the date of the Jan mock, but the result they think most likely if they had sat the exam in May/June, having finished the course.
So many parents are sure that their child is the clever but lazy one, who somehow did very little though the course but was going to ace it in the exam. Sadly, when the final result comes in, quite a lot of parents and kids will still believe that would have happened and blame the system. However, the reality is that for the vast vast majority, a holistic consideration of their performance and ability across the whole course does give a very good indication of final performance. Teachers are sometimes sunrises by how poorly some students do but less often surprised by someone turning out to be brilliant and pulling it out of the bag, that they never spotted before. In most cases, the teachers have got a good handle on the students.
For all theses reasons, I think that the results issued this summer will reflect what would have happened in the exams. Of course, statistically the results will because the government will make sure they do, to ensure comparability wi other years. That is very important. And then for each school, they will be comparability to previous years too, unless this cohort is significantly more or less clever than the previous ones. That's what the exams would deliver too.
With A Levels, as always, many will get a bit lower than their UCAS predicted grades and their first choice uni might still take them or they will go to their 2nd choice, or they will get a place through the large Clearing system.