Is it some reason why no one from watercooling manufacturer not made stainless steel fittings.
We know how that material and different types of stainless steel could be durable from knives and other parts.
They would last 100 years easy if you clean them.
Residues of everything much harder stick for stainless steal and much easier clean with normal detergent for disches or alcohol or hot water.
Off course it would be nice without any printed logo, engraved if need.
Every 2-3 years you replace rubber o ring and that's it.
They could shine much finer than nickel and brass and have specific recognizable matt shine,
specific noise when you keep them in hands and can't corrode in normal environment.
 
In vaping industry most expensive tanks are stainless steel with gold plated contacts and borosilicat aka pyrex glass.
Cheper variants are brass usually, or even more expensive clones are stainless steel. That would be amazing stuff, probably double higher price but far better than any Bitspower, Barrow or etc fittings.
 
Maybe someone know reason why they not use him, some specific. 
 
If someone use vaping equipment, tanks, drip tips, etc from stainless steal you will notice how that material is superior.
And leaking depend only from O-ring. 
 
This is stainless steel, have specific sound when you touch two parts or when you screw them...
Imagine compression fittings of them with engraved logo of brands...
 

 
 
My estimate is that one compression fitting of such material can't cost more than 15-16$ max.
But remember these are high quality parts produced to unscrew them every day even more times to last years.
Fitting you put once and he stay month, stainless steal thread is far more durable and could be build precise as any materials we see today used for adapters, barbs, compression fittings.