Personally from my college experience I know that I have used my laptop in lectures for both good and evil. I have legitimately used it to google work, ideas and to open tabs on papers/etc. to read later. I also used to write code in all my programming lectures because programming lectures were dull otherwise, might as well make use of the time. However, there are many times I have opened up reddit or HN during lectures and 'checked-out' as the article suggested.
Sometimes I have paid for not listening to the lecture but the majority of the time it doesn't matter. The idea that I learned my college curriculum in lectures would be a joke. As a computer science student I learnt my trade in the labs and tutorials and interactive courses rarely from listening to a lecturer explain X, Y or Z.
The better the lecturer or the harder the module the more laptops that were closed in my lectures. My compiler design course for example, infamous for being the most difficult module no one dared open the laptop as there was too much knowledge to consume.
Lecturers can easily do a self-assessment survey of how engaged their class is and how interestingly they are presenting their material but how many heads are hidden behind laptop screens.
For the one lecturer who did ban laptops I have to say I went to absolutely none of his lectures unless I had coursework to submit. I found it a bit presumptuous that he could demand I close my laptop, I was not distracting him or disturbing the class.
You don't learn in lectures where lecturers read their slides to you laptop open or not. If the lecturers are going to waste my time with pointless reading of slides then I might as well do something useful on my laptop like my coursework or just read hacker news.