steam is unproven? Ooops, I guess i've been playing on an unproven system for half a year now. And tens and tens of thousands of people have bought CS:CZ through this unproven delivery system. I wonder if they knew that when they successfully purchased and played on this unproven system. Someone should let them know. Maybe you should write them an email, Voodoo.
When they were getting to the point of getting a publisher Steam was still in it's infancy so they went with VU in case Steam tanked so users could still play HL2 when it was ready.
It's called planning for the worst.