Anyone is welcome to purchase a copy of Ebony magazine. It's targeted, but it's not exclusive.
And if this isn’t really any better, where does that leave you?
If your local newspaper could print a special edition for minority subscribers that didn't include job listings, that would be a problem. Advertising in a special interest publication is not, on its own, a problem. Of course there's no clear lines in reality, everything must be evaluated in context.
Let’s take a company like REI: is it wrong for them to put their stores in places that are most profitable? Should luxury good companies be required to have store fronts in inner cities?
I’m legitimately not sure I’m comfortable with either answer. “Women / older people are unlikely to respond to this ad; so we’ll have a better ROI by excluding those groups” feels awkward but like a legitimate business interest. If I sell male hygiene products can I exclude women from seeing the ads, not because I don’t like women but because the ad is less likely to be relevant?
“I don’t want to work with women or older people so I’ll not show them the ad” feels unquestionably wrong.
I think you have to consider intent as well as outcome.
That's not what this thread is about. The question here is what is the difference between advertising on Facebook and excluding some demographics, and advertising in a paper magazine where you don't have the power to exclude anyone from viewing the ad.
If facebook displays housing ads only to white people a black person is very likely not even aware that they're being discriminated against in some specific way, the entire control is in the hands of facebook and the ad buyer, and intransparent.
The situation would be equivalent if facebook gave you complete control over their algorithm and let you choose what type of ads you want to be exposed to. Which would make discrimination much less of an issue. Or the other way around, the current facebook situation would be akin to the store owner quickly cutting the housing ads out of cosmo as soon as black people walk into the store.