As I said to the previous poster, if you have a shred of evidence that "the feminists" consider this app to be acceptable (not just "less bad"), you should share it now.
If you don't, then you might want to pause for a few minutes and seriously ask yourself why you said what you did. Because from my experience, opposing a service like this is a core value of feminism. (It may not be seen as a top priority, but that's a radically different statement.)
I think you and duaneb have misunderstood my comment. I do not mean that they will say that it is acceptable to them because of the patriarchy, they will say that it is acceptable to society because of the patriarchy. In other words, they will blame the existence and acceptance of this app on the patriarchy and not the individuals who created it and accept it.
Ah, thanks for the clarification. (I'm not sure that I understand your point, but at least it's not the basic misunderstanding of feminism that I thought it was.)
(This is a reflection of the social influences that feminism labels "the patriarchy", right? Even though it's individual people making choices that implement those social trends. I've never considered the two to be mutually exclusive.)
Most (all?) women I know who identify as feminist activists would not support this app, and I highly doubt anyone who would is really a feminist. This is equally harmful to women.
Don't worry, they are certainly ready with the argument that it is the "patriarchy" that makes this app acceptable but not the reverse.