Thanks for responding! I didn't say you were focusing on 4e, but that notion that 4e PCs are invincible supermen keeps coming up.
It's not that they are invincible and it's not that they are supermen.
It's that they are nearly invincible. It's difficult to heavily challenge players without going overboard. One almost never sees just one PC die or PCs significantly penalized after a fight. Either the PCs can handle the fight and all PCs survive (and except for some mostly renewable resources, are basically unscathed for the next fight), or multiple PCs die up to and including a TPK. There doesn't often seem to be a middle ground after a tough fight and PCs typically get up and brush themselves off with little in the way of future penalties or concerns (shy of the rare DM that hands out diseases on a semi-regular basis, poisons do not even last beyond the encounter).
And they are not quite supermen, but just superheroes (who came to Earth with powers and abilities far beyond those of mortal men).