Selection bias renders your question unanswerable in the general case, but in the specific case of someone with 5 years+degree versus 10 years+no degree, I don't believe you will be able to back up your assertion.
Given the statistics, are you saying that most high tech companies have incorrect hiring practices?
You haven't given any statistics, so this question is unanswerable in context. Companies hire based on the candidates available. In certain fields, virtually all of those candidates will have degrees. That's all that can be stated with any certainty.
Do all the bean counters who measure productivity not have any influence in who gets hired? OR do employees with both education and experience outperform those with experience only?
These questions are also too general to be answerable. I would, however, note that some of the larger employers including Dell, Apple, and Microsoft have no moral authority to reject undegreed candidates blindly. Perhaps that's why they don't.