What the thread points out is that the exam results have _always_ been a rubbish approach. They're a way of slicing the kids into layers of competence, so that employers and educators can skim off the layer they want. If everyone does well then the grades are adjusted to make the results fit a curve.
And, on top of that, judging everything you've learned in a course by a single letter makes no sense. A course may teach you dozens of skills, and to then give only one single letter to represent that is ludicrous.
My preferred method would be that you either understand something or you don't. Break a subject down into atoms of understanding. People then learn those, and build new ones on top of ones they've learned. This would have two effects: (1) you'd be able to see if the person had the actual skills an employer needed (e.g. needing long division, not caring about geometry) and (2) it would highlight places where teachers were trying to teach more complex knowledge on top of basic knowledge that the person didn't actually understand yet. ("Bob, you're trying to teach my kid long division, but he clearly hasn't understood basic division yet"). This was something I saw fairly regularly as a child - kids left behind as the classroom swept on, when a little more work on a few basics might have given them the chance to catch up. If they were lucky then a parent might help them get caught up.
I'm not convinced our current teaching setup would work well with this. But then I think our current teaching setup doesn't work for a ton of people**, and I'd like to see us look at ways of making it work for far more of us. I hate to think how many other people are let down by a system designed to mush everything into "This person, overall, understands this huge area better than 90% of other people." - a grade which seems useful for gatekeeping people moving on to the next level of the same subject, and not much else.
Edit: A grading system I would be comfortable with would be to mark people as "Can repeat by rote", "understands concepts", and "can explain concepts to others".
*No exams this year, so grades were given based on prelim exams and teacher predictions. But the exam authority moderated down the predicted grades for children from schools where exam grades were historically lower, effectively saying "You come from a poor area, so we don't believe that your results could be that good." The defense being that even after this downgrading, more people from those schools got good grades than they did last year - in other words the predictions were not reasonable. There are clearly a lot of unhappy people, and this is going to take a while to unpick. More details here. For clarity, this is not just a Scottish problem, the front pages of the papers today say that 40% of A level (English and Welsh exams at 18) results will be lowered.
**To give a personal example, I took three attempts to pass my English language exams aged 16. I have no idea why. I read voraciously. I understood English pretty much as well as I do now. But the exams were asking questions where I literally did not understand what they wanted me to write. Instead, measuring my understanding of specific points, making it clear what it was they were asking me to prove I understood, would have been a huge benefit to me.
Original post on Dreamwidth - there are comments there.