The 1960s, what a load of rubbish.
I failed the eleven plus and went to a secondary modern. We were not treated as failures and we did not spend our time laying bricks or typing. Nor did we herd cows.
In many cases we received a more rounded education than those at grammar schools. But hey, let's go with the myths and legends. They are much more entertaining for the modern world where 50%+ of pupils go to 'Uni' to learn what we learnt at 3rd year CSE.