I dislike it when people say "Valve knows (blank) as they did something similar years ago." The tf2 team is - to our understanding - a completely different roster of game devs than the devs when the game launched.
FUNKeBleghfuricvalve is going to try to turn 6's into hl
Valve knows classes are meant to be specialist and generalist, the game was designed to work that way
They just don't want to force people off their favorite classes (spy/pyro/engi/etc) so they're doing this half-assed effort to allow players onto the classes and not actually provide any in-game tips or popups saying shit like "ENGI AND PYRO ARE GREAT DEFENSE CLASSES BUT LACKLUSTER ATTACKERS, CONSULT YOUR TEAM ON WHEN THE BEST TIME TO SWITCH MIGHT BE!"
So valve certainly knew this at launch, and the comp scene is trying to hammer it home now, we still have to hammer quite a bit as they seem to be spinning their wheels.