To be fair it wasn't a rant at you - more the system. The school implied very heavily in favour of BMI but we just destroyed the letter and didn't tell Miss W about it. My problem with it is that it seems to have become the defacto standard - just look at the BBC article - with no warnings given...
It is flawed because it's promoted as the best way of telling if you're overweight and so too many people take it as gospel. It's far too basic. We got a letter from my step daughters school when she was 10 saying she was overweight and that we should do something about it. No account was taken...