I don't think public breastfeeding is as common as it could be. The first time I was "exposed" to someone breastfeeding in a public space (I'm discounting 'breastfeeding rooms' here) was about ... six years ago? And it was a friend I was with.
I was raised an only child, of course, which limited my exposure in-house, but the stigma against public breast feeding was pretty strong in a lot of areas for decades, and the fact it's still an issue today in other areas speaks well enough to how slow public opinion (or rather, public policy) is shifting in favor of breast feeding parents.
I just don't think it's an issue of fapping in this case - because let's face it, people are fapping on the internet all the time, in chat rooms, watching videos and streams and all sorts of nonsense that is plenty non-sexual . . . they just usually have the decency to not say anything.
It's an issue of "indecent exposure," which has never been about what people fap to: it's been about policing bodies.