Is it, really? Or is it more often than not just a facade for the same old hiring practices. Faced with someone who "loves gardening!!" vs. someone who has a ton of OSS contributions, who are they really going to hire?
However if we get a more competent candidate who likes gardening more than programming, we'll absolutely choose them over the pure passion person because they'll do the job better. They just have to show that competence in some other way, e.g. via the interviews or past job accomplishments.
On the other hand, I can't imagine someone with tons of OSS contributions who _isn't_ passionate about programming at some level.