Where I work, the marketing department is always putting horrible newsletter popups on the web page, etc. I used to say, "That's going to detract from people signing up, not encourage it!". But they've got the data and they've shown it to me. As you say, it works.

I wondered why for a while, because as soon as I see those shenanigans, I'm gone. But then I realised: I'm not the target market for the websites we have at work (a full service travel tour company). Most of our clients are booking travel for a group of 30 people from their company 6 months or a year in advance. They are coming to our website because they want the damn newsletter. Took me a long time to understand that.