Totally disagree. When buying ANY "K" series processor, you are paying a premium for the "K" so you can overclock it. And should be able to play the silicone lottery yourself. Not have a guaranteed poor overclocker. In which case just buy a non K system. People buy "K" to overclock them, not to run them at the "frequency advertised". Fact.
But a pre-built system already comes overclocked at the frequency advertised. You want a higher clock, you buy a better performing pre-built. I've not met someone who pays a premium to recieve a pre-built machine that's been OCed by a pro, only to scrap all the work that's gone into it and try to OC it themselves. Have you? What was their motivation for spending that amount of money on labor only to go ahead and try to do the work themselves anyway? That's like paying a chippy to put your doors in, then tearing them off once he leaves and trying to do it better by yourself.
Your argument works when you're buying the boxed retail processor by itself, but you were talking about pre-built systems, that's a different ballpark.