I used to fly a 300 that was incapable of pressurising from take-off single pack 'cos it leaked so much
See your twaddle and raise you a balderdash !
One badly maintained aircraft does not mean that the type is in someway deficient, we have an ageing 300 fleet any of which that can happily operate on one pack if the necessity arises albeit at a reduced altitude of FL250.,
I call that putting the theory into practice.