And those mobile devices have much more conservative limits, and much more aggressive throttling behavior.

Smartphones have no active cooling and are fully dependent on thermal throttling for survival, but they can start throttling at as low as 50C easily. Laptops with underspecced cooling systems generally try their best to avoid crossing into triple digits - a lot of them max out at 85C to 95C, even under extreme loads.

For handhelds the temperature of the device's case is one factor as well when deciding the thermal limits (so you don't burn the user's hands) - less of a problem on laptops.