So, in my circles, the phrase "purity culture" refers to the harmful & abusive attitudes & behavior around sex & sexuality in religious communities (especially within evangelicalism).
I'm seeing discussion of Cory Doctorow's use of the term "purity culture" to mean something like people who are (supposedly) so obsessed with being perfectly ethical that they harass others and...I dunno...halt progress. I guess he's not the only one who uses it that way, but it's news to me.