I used eGPUs long before they were 'cool' and used them via express card slot on old Thinkpads. They were a decent solution, but had serious issues with bandwidth in some games. Now with TB3 I've got XPS 13 and an eGPU and I'm extremely happy. This was the ultimate solution to whether have a laptop or a desktop. Gaming laptops were alright, but they were always inconvenient to carry and they tend to end up with GPU hardware issues. Of course I also got external monitor, keyboard, speakers, mouse, gamepad etc., so when I play games now my laptop is just a 'case', but when once in a while I want to take it I just unplug three cables and that's it.
Obviously I bet one could get a bit more performance using desktop tower, but honestly, the hardware advancement slowed down so much in recent years it doesn't matter to me much anymore, even though in the long past I was buying new towers every 2 years to play new games.
For those who play competitively new games I wouldn't recommend it, however, for many other it's just perfectly fine.
That said, not everybody wants a laptop anyway. I just know I do. It's great we have another option for us, so people can choose whatever suits them.