It seems more and more common, when you enter a page and start reading it shows a popup after ~10 seconds. Personally I just leave the page immediately and look for the content somewhere else. I can't imagine anyone likes being interrupted by some pushy message about subscribing or whatever. What is the intent with these things? Is there any reason to believe this is an acceptable "feature" to put on a website? Bonus: is there any data about number of people who leave the page right after the popup shows?
Sorry if this seems more like a rant than a question, but I'm really wondering why one would choose to include this on their website. I can't imagine any reason that outweighs the possibility of visitors getting annoyed.