'Targeting your ad spend' is the thing under fire here, and under a very specific attack.

Before online advertising you kind of had an idea of what the target audience of TV channels, news, and radio was like, but it was very fuzzy and you certainly weren't excluding people not in your target demographic that happened to utilize those media platforms. Women reading male fitness magazines or men reading female lifestyle magazines weren't the primary target of ads in those platforms, but they could certainly utilize what was being advertised if they so desired. The same is not true of online advertising today.

Facebook is more in the position of a newsstand than anything else, and it would be blatant discrimination if a newsstand wasn't allowing older people to buy technology magazines, for example.