When people say the ‘CPU’ in this thread, they don’t mean the whole main computer unit, if that’s what you’re thinking. They mean just the little chip inside. There’s a cooling system so it isn’t actually anywhere near that hot on your lap.
True. But I've used laptops where the fan exhaust was unbearably hot. And I'm sure that was much cooler than 90°C.
So maybe someone could check exhaust temperature on a 2018 Macbook Pro with i7 under heavy load. I get that the exhaust ports are on the back, near the display hinge. But that still might be iffy, for those who cross their legs.