Prime95 is basically a synthetic workload so it makes little sense to optimize for it.
Temperature junction throttling is a last resort. No laptop should rely on it in normal operation. Of course, both HP/Dell/Lenovo/etc and Intel benefit from increased sales so they don't care.
At 100 the processor is at high risk of damage, which is why there's a built-in throttling mechanism.
Just imo, if it was safe it would be running at full speed (or at least max base clock) at that temperature.
As someone else said, they're made for burst operation these days, but again, that does not excuse manufacturers using subpar cooling.
I can see the majority is fine with it, but I'm not. A 15-25% failure rate in 2 years would make any other product a rotten lemon. But somehow it's acceptable for computers. Probably because people replace them every 2 years regardless, which is another insanity on its own.