It's by necessity. The hardware in a gaming laptop gets a lot hotter, so you need wider openings that are closer to the heat generating parts. If you were to do this on the sides, you'd need to build the case bigger and put a much stronger heat transfer system to account for the smaller and further opening.
I think that it’s fairly safe to say that nobody uses a gaming laptop on their lap when gaming, particularly mouse and keyboard players. I only use mine when I travel for work, and I bring a proper keyboard and mouse with me.
That said, I do occasionally use it on my lap. When not gaming, the heat produced is pretty low and it works just fine. It also has small intake vents on the side.
Even my “corporate” Thinkpad with no dedicated GPU has all the fans on the bottom and exhausting to the sides and back.
With the new hinges there’s space on the back for exhaust, some impeller fans drawing from the sides and exhausting out the back would be so much better. I custom printed some 1/2 inch high feet so it doesn’t throttle sitting on a table or lap desk because it’s just a terrible design even when used normally
I had the same thought as you before and one of my friends said “many people don’t call them ‘laptops’ anymore but instead call them notebooks”.
I found that name very fitting. Barely anyone uses their (gaming) laptop on their lap anymore. Usually on a desk in a thing that holds the laptop up to ventilate.
Note: I don’t know the exact name of it in English.
The industry actually tried to get people to stop calling them laptops because people kept burning themselves badly in the early days of portable computers when they would get hot af
It doesn't, the assumption is that users will not use them directly on their laps for heavy loads.
There isn't much they can do. There isn't enough room on the sides to vent all of that heat. This is the tradeoff you make when you ask for 200 watts of performance in a laptop form factor.