And what makes you think that isn't already happening? I'm sure there are beta testers from this website that have signed non disclosure agreements and can't talk about things at all because of those agreements.
If that's the case then they've got the wrong testers from this forum. It takes about 8 hours or less for a dozen or so specific users here to find a slew of new bugs after every release. Isn't the point of beta testing to find the bugs BEFORE the release?
I think we all agree that we could do better.