It’s because an silicon chip, which with 140ºC begins to degrade, the reason why they use an thermic security which desconnect the device on critical temperatures, but even so 110º isdefinitively to much and also will degrade the chip if it ocurred repeated times.
I don’t think that’s planned obsolescence. The limits on laptops are usually higher than the limit on desktop PCs.
And I had a ~110°C threshold as well on a Dell laptop running Linux, so it’s not just 'a Apple thing.
It’s because an silicon chip, which with 140ºC begins to degrade, the reason why they use an thermic security which desconnect the device on critical temperatures, but even so 110º isdefinitively to much and also will degrade the chip if it ocurred repeated times.