I've implemented these as well, they're not my favorite and it wasn't my decision to add them. However, after a certain point, for those popups which only appea

I've implemented these as well, they're not my favorite and it wasn't my decision to add them. However, after a certain point, for those popups which only appear after engaging with the content, there is some validity to the idea of this as a form of progressive signup/engagement. Second, newsletter popups, with exceptions such as {Pinterest; Quora; Cook's Illustrated} these popups are not a pay-wall. The better criticism is of the poor interaction design of such systems that don't treat any click outside of the modal as a modal exit command.