In the past, it was used for the genderless or anonymous. However, this usage is viewed with disfavour by many, though it still has its supporters. I use they for these cases, a usage which can be found in literature of earlier centuries.
But didn't that disfavor [STRIKE]didn’t[/STRIKE] stem from feminists? no comma here I’m questioning this because someone claimed it was some feminist agenda.
You won't find a definitive answer to this question. No doubt there are some political agendas that favour/disfavour certain language use but there's also simply the idea of equality.