"They" can be either singular or plural.

http://en.wikipedia.org/wiki/Singular_they

  Women are not underrepresented in technology because of male-gendered
  pronouns in code comments.

I don't think anyone is seriously suggesting that.

  As someone in the earlier discussion suggested, if you want to make a
  difference, quit complaining about pronouns and go help mentor some girls at
  your local school [...]

I believe promoting more inclusive language does make a positive difference. Regardless, can't one do both of these things? I don't see how they're incompatible.