IT people are just like normal people. In fact they usually are normal people ;) You might further distinguish front-end developers, I'd expect them to click on much more things to figure out what makes them work well or not.
What happens when most people browse the internet is that they scan pages for interesting content, to answer a question that they have. Does this site sell shoes, where do I buy a ticket, can I call these people on the phone, etc. People have learned to ignore everything that looks like advertising, in part because even the things that aren't don't help answering their questions.
Nielsen mentions that his findings do not apply to search engine ads. This perhaps has to do with their design (hardly any images), but also because they actually help the user answering questions. Eg. if you're looking for a product, the ads might help you find an actual webshop amidst all the aggregators and "review" sites.
So it isn't so much a question of people not understanding what a carousel is or that they never click ads. There is nothing IT personnel know and others don't that would make them interact with carousels.
You should be careful in extending Nielsen's research findings outside the research questions that he's answering. He's found out that people do not read the content that's in a carousel and that people skip anything that looks like advertising. So a clear finding is that carousels should not be relied upon for content. However, you'll see that in his heat maps all images are skipped, even inline images in content. You could conclude that we should do without images completely. However, I think you will agree images (and advertising) still have a purpose.