Of course, but that went for de Villota too, and de Silvestro. Sirotkin is only their because of his money. Ma Qing Hua too. And countless other test drivers who have been added to a teams roster purley for reasons other than their skill.
Ma Quighua seems to be pretty much slam dunk on that point (really, what is he doing in a F1 seat?) but every other F1 driver you've chosen to mention actually has a decent record that justifies their initial placing; Wolff doesn't.
And she actually seems to be getting extra flack for wanting to try and prove herself too. I don't rate her, but given what means people are 'buying' seats by out there, Susie having a couple of Friday runs is hardly the worst thing to happen to F1 in the history of the sport...
I think it's a great thing she's got some run outs in F1. I'm not sure we'll ever see a female driver compete at the top level in the modern sport but people like Wolff getting even a bit of testing increases the chances that if someone does come along with the talent needed they'll actually get a shot at proving they can make it.