Only in the weirdly defensive world of Hacker News does preferring people who contribute to open source software imply throwing out resumes without it, does it imply "missing out" on those people. Of course I consider resumes without open source work. It would be stupid to not do so. But I will look first at those with a publicly auditable track record. Is that a surprise? I look, earlier in the list, at people who've worked at a number of large firms with strong technical teams, too. They shrink the error bars on hiring.
Though, even if it didn't mean I was getting a view into how they actually work, I'm okay with preferring public-minded people who give things back and make the world a better place through it. I try very hard to live by the motto "pay it forward" and I find it to be rewarding and pleasant to work with those who do likewise.
> Then pay them for it.
My last two employers did exactly that. Should I need to hire directly for my consulting adventures, I'll do it there, too. I mean, this reply makes no sense to me: why would I not?
> I think open source development is virtuous and is something that I want to promote and encourage
Then pay them for it.