I think there is selection bias, but in the other way. Web programmers, as your typical HN goer sees them, probably tend to underestimate just how many other programmers there are out there, particularly doing Java work.

Beneath the bleeding edge of "what is cool" and "what cool companies use" there is a very large iceberg of people and companies doing/using things that stopped being cool a decade ago.

Well, it looks like the overwhelming majority of web programming is done in PHP/ASP, so I guess it's not the case so much for web developers.

Although I'd be amazed if Go won over a significant portion of the PHP/ASP crowd, given that they have already self-selected out of using Ruby, Python, etc. for web development instead.

I suppose you could argue that Go is a good fit for PHP/ASP programmers who have really tuned their applications for performance, but I strongly suspect they're a small minority.