Well lab glass condensers are specifically designed for cooling vapors - that's why it makes a great material for vape stems. Most of the spiked stems on the market are just a play on the Vigereux Condenser. Personally I feel that cooling vapors is very different from designing a CPU heat sink that doesn't deal with delicate volatile aromatic compounds at all (I think lab purity is important since our vapes essentially function like a mini lab setup.) Honestly I don't know anything about processing uranium, but I do know that the distillation of cannabinoids is done with glass and that's as close as it gets to what us vaporizer enthusiasts are doing at home.
Why would you want a vaporizer stem that is not inert to almost everything? Metals readily react with vapor and change the composition, resulting in obscured flavor profiles. This is why a dab off a titanium nail will never taste as good as a dab off quartz, despite titanium having far superior thermal properties on paper. This is important since many will claim that titanium itself is "inert," and I know this is the Dynavap thread so I'm walking on quail eggshells here... but the proof is in the pudding.
As far as "it," I'll give a quick and familiar example of why there is more to heating and cooling than thermal conductivity. You'll like this one as its inspired by the great Max Planck himself! Take two cotton t-shirts with identical thermal conductivity, one dyed black, the other white. When standing in direct sunlight, why does one shirt feel hotter than the other, despite identical conductivity?
A: emissivity is important too!
Don't get me wrong, thermal conductivity is useful but also kinda overrated: I remember the first time I tried silicon carbide as a vapor surface, 150x more conductive than my quartz banger on paper. It's not really 150x more efficient or effective in real life though, in fact I still ended up preferring the quartz for its neutral flavor.
Of course the real answer is that vapor hates being cooled, no matter what the surface is.
