Well, let's put it this way. For every great new, improved idea, there are dozens, hundreds, thousands of wannabees. After hearing many dozens of times about how great something is, and getting disappointed (or burned, if you believed them without checking), a bit of cynicism is to be expected.

Your question is much broader than programming, of course. How does anyone ever tell the difference between the genius and the crackpot? To reject the claim is a self-fulfilling prophecy. You deny that they have a valid idea. Nothing comes of it. Therefore, it wasn't valid. It's fallacious, but safe, because chances are good you won't be proved wrong.

If you accept the idea, then you risk it being shown to be invalid. If you've committed lots of resources to it, you may be harmed - lose time, money, reputation, whatever.

I once read a comment by a physicist (I don't remember the book or the person). He said something to the effect that he wasn't sure he'd have recognized Einstein's papers of 1905 for being works of genius. He might have dismissed Einstein as being a crackpot, with his crazy ideas about space and time.

For every Einstein, there are endless Bozo's out there. If you have no better way of judging, then defaulting to skepticism will almost always make you right.

At the end of the day, only time will tell whether a new idea is a better idea. People will have to try it out, test it, play around with it. There are probably many unsung geniuses out there whose ideas were ridiculed, ignored, maybe even forgotten. That's unfortunate, but it's bound to happen. We are likely to err, false positives and false negatives being unavoidable. But the price of a false positive is immediate and can be severe. Jumping onto a new, but wrong, idea can be very costly, and you'll usually find out fairly quickly that you've been burned. Ignoring a genius might be more costly to the world in the long run, but it's safer for the decision-makers, and the error won't usually show up while it matters to them. Or does that sound cynical? ;-)

That's what open source and peer review are all about. The code speaks for the coder (sometimes the coder gets to speak for him/herself too, when asked), and the community sorts out the competent from the incompetent.

Of course even in this arena, whether a good piece of open source code really gets the usage and notariety it deserves may still be a hit-or-miss, luck-of-the-draw kind of process. (And it's possible that some really poor code gets into the "standard tool set" for a while, but sooner or later, it will get phased out.)