No, it doesn't. It means that they add massive value and more people buy more games as a direct result of the value that they add. Valve has done more to grow the PC gaming space than anyone else and there isn't anything close.
They could take 50% and they would still offer by far the best value out there with nothing else close. Their cut is extremely generous to developers.
Epic is the only one offering a meaningfully different cut from anyone else, and they're doing it by being absolute dogshit at everything connected to their store in any way.