Well that's where you're wrong then. It's perfectly possible to game on a laptop. Over the last decade with the development of the lightning ecosystem and docks it's become a very low friction endeavor as well.
There are a myriad of quality "gaming" laptops out there, but obviously that's not for everybody, and that's one of many reasons why workstation laptops exist (basically the same thing - ability to run at high loads for extended periods of time - without the gamer aesthetic).
There are many casual gamers out there who don't want to shell out for a dedicated gaming device, nor should they win a laptop is a perfectly adequate device to game on. It's not that hard to comprehend.