What? That is just wrong. Zen 4 are not "designed" to boost to 95c. They work just any other cpu ever did in the history of cpus. They boost until they hit either a power or a temperature limit. That's literally how any other cpu works. But because they are actually HARD to cool, they reach a temperature limit before they reach the power limit.
Not sure if you are aware but 95c is the target temperature of Zen 4, aka the temperature the CPU will advantageously boost to. You can verify this in every review of the product as it will continue to boost until it hits that temperature and will scale frequency with that value in mind.
Historically speaking CPUs relied upon a frequency and voltage table and would throttle back down to a lower frequency state if they hit a thermal limit. Boosting is relatively new to the CPU space, which started around 2009 with Intel turbo boost. To say that CPUs always boosted is patently false and also ignores the difference in how AMD's boosting algorithm or how boosting algorithms work in general.
If you take a look at AMD's boosting algorithm for the 3000 series vs the competing Intel products at the time, AMD is able to update it's boost algorithm with the 3000 series once every 2 ns. If I recall correctly Intel was something like one update every 32nm.
That some Zen 4 processors, specifically the X class, frequently sit at 95c tells us two things. One, AMD's boost algorithm is taking full advantage of thermal headroom. Two, Zen 4 CPUs have a target temp of 95c. Any use of that value to imply that they are hard to cool would be despite the plentiful reviews like ones the graphics above were pulled from, clearly showing that Zen 4 with far less cooling grunt that competing high end Intel processors.
Saying zen 4 is easy to cool is just factually wrong. Their heat transfer is bad both because of ihs and big density.
The IHS narrative is just an assumption without anything to back it up from the reddit community and surely your reddit friends know more than AMD engineers on optimal die thickness.