Although you can buy the CPUs in TRAY format without the cooler, the prices are almost identical to the BOXED version and your warranty is lower since they're designed to be sold to businesses not consumers.
I think this is exaggeration. I have 3600 with stock cooler and at full load clocks doesn't seem to fall below 3.8GHz, 86°C (well, I tested on linux make -j12, maybe on some AVX loads it is worse).
Funnily enough, siege has recently released a vulkan based build that runs at a cool 74 degrees.
The wraith stealth is just an incredibly anemic and disappointing heat sink. It's "functional"but only at average loads. This is in comparison to the previous generation's cooler for the midrange CPUs that was about twice as large. It's not a deal breaker, my 3600 is still miles above anything I've ever run previously, and it isn't dying under the heat, but it might just run one year less than it was initially designed for at those temperatures
My own Wraith Prism is just sitting in the basement, and I don't see myself ever using it, unless something happens to my high-end cooling system and I need to install something while getting it fixed, at which point it'll go back to the basement again.
It would be interesting to see statistics on how many Wraith Prism coolers sold together with 3900X CPU:s actually end up being used. I expect the number to be quite low.