Yo. There's no proof that a great by-product produces a great product. Read the memo by Marc Andreessen about product-market fit. You can nail by-product and still miss the product. But of course, like Marc Andreessen said, it's popular for employers to champion "we care about our hires" (because who would do the opposite?)
Since I can't update the post anymore, I just wanted to apologize for the tone of the comment above. It was a knee-jerk reaction, and there's no need for me to sound like that.
Update: This post suffers from a cause-and-effect fallacy, and hindsight bias. More: http://times.jayliew.com/2012/10/12/cause-and-effect-fallacy...
So many developers are falling for this. Wake the F- up.
The irony: Zach doesn't realize he's talking like a pretentious Steve Jobs. Until you can prove cause and effect, please stop tricking developers. Yo.