It’s branding, mostly. The phones had a notch. Design language dictates that the laptops can too, since it’s Totally Not Ugly (but it is).
Also, macbooks are slightly taller (16:10 aspect ratio) than most Windows laptops (16:9). Slightly taller even with the notch, since the extra screen is on top of the 16:10. So there is admittedly not much room to fit a camera on top. Personally I would prefer a slight bulge at the top and a rectangular screen, but with a black background, it isn’t too awful. Drives me mad with any other colour, though, I just can’t unsee.
I wonder if Valve will eventually offer their own system of checks similar to Google Play Integrity? I don’t think I’d care for it since it’s an invasion of personal choice on a device that you own, but for people who want to play competitive games with cheating problems, running a partition with integrity checking seems a fair trade.