> How many Oxford graduates actually remember everything they were taught?
Nobody remembers absolutely everything from any course of study. However, graduating with good marks from a university like Oxford shows that an individual is capable of succeeding in a rigorous environment.
> How many cheated their way through the hard parts?
Most likely more than zero, and this is something you have to take into account when addressing the reputability of an institution. Oxford in particular does have issues with cheating, but most of the discovered cases seem to come from their business school, so even different programs from the same university might have different reputability.
> The only solution is to evaluate a candidate directly
That's obviously false. That is one solution, and clearly the one you prefer, but it is not always (or even often) practical.
Nobody remembers absolutely everything from any course of study. However, graduating with good marks from a university like Oxford shows that an individual is capable of succeeding in a rigorous environment.
> How many cheated their way through the hard parts?
Most likely more than zero, and this is something you have to take into account when addressing the reputability of an institution. Oxford in particular does have issues with cheating, but most of the discovered cases seem to come from their business school, so even different programs from the same university might have different reputability.
> The only solution is to evaluate a candidate directly
That's obviously false. That is one solution, and clearly the one you prefer, but it is not always (or even often) practical.