Why do you think standards have been watered down in the education system?

EDIT: Thank you for the interesting discussion. To be clear (as I didn't emphasise this originally), I do understand, and appreciate that things have become more accessible, and standards have been raised for the average student. And this is good! My point was just that this has potentially come at the expense of stretching the brightest, which is costly for them and potentially us as a society if we're going to get the geniuses of the future. Surely, there is a way we can do both!

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This has taken place over a long time. The maths, English and science courses my children studied were less advanced that those I took when I went to school, and looking further back, my grandfather studied calculus in order to get IN to grammar school. It's not just academics either. I taught PE, and it would've been impossible getting most of today's students to do the fast-paced intensive gymnastics routines we sometimes had them doing in the 80s for example.

And then there's behaviour. The disruption that goes on in some schools nowadays would've been unheard of a few decades ago. It's simply about enforcing the rules, teachers demanding respect as professionals, and parents supporting them.

Clearly, the education system caters for more abilities so more can study, but does that have to come at the expense of supporting the best and brightest? Why do you think we've allowed this watering down of standards?