I have never really found it persuasive, personally, although I like it a lot more than the quotas-for-quotas sake rationalization. Here's my beef: people are Ruby objects, not Java objects. They can have all sorts of weird behavior added at runtime that other instances of the same class don't have.

You could, for example, monkey patch an instance of Female on the fly with acts_as_fps_developer, or have an instance of Male which responds_to develop_product_for_female_audience. Moreover, this is not weird or unexpected in any way. So why would you assume that your ability to develop_product_for_female_audience increases linearly as the number of developers who are instances of Female increases?

Instance of: it's a code smell in Ruby, it's a code smell in hiring.

(Yeah yeah, I know, Java can do dependency injection these days. It's a metaphor, deal.)