I mean sometimes it's true. Like even in the past. I could very clearly see amongst my generation (older gen z) that there were plenty of people literally at university who were barely willing or able to learn. Comparing that to the generation of my much older half siblings (genx, older millennial), they don't even seem to grasp the concept of not being quite involved in your university degree.

Most people my age will tell you that they stopped reading as a teenager because of the effect of smartphones. I was a veracious reader and only relearnt to read last year after 10 years since I got my first smartphone as an older teenager. These things are impactful and have affected a lot of people's potential. And also made our generation very prone to mental health issues - something that is really incredibly palpable if you are within gen z social circles like I am. It's disastrous and cannot be overstated. I can be very sure I would be smarter and happier if technology had stagnated at the level it was at when I was a younger child/teen. The old internet and personal computers, for example, only helped me explore my curiosity. Social media and smartphones have only destroyed it. There are qualitative differences between some technological advancements.

Not to mention the fact that gen alpha are shown to have terrible computer literacy because of the ease of use, discouragement of customisation and corporate monopoly over smartphones. This bucks the trend that happened from gen x to gen z of generations become more and more computer native. Clearly, upwards trends in learning due to advancements in technology can be reversed. They do not always go up.

If kids do not learn independent reasoning because of reliance on LLMs, yes, that will make people stupider. Not all technology improves things. I watched a really great video recently where someone explained the change in the nature of presidential debates through the ages. In the Victorian times, they consisted of hours-long oratory on each side, with listeners following attentively. In the 20th century the speeches gradually became a little shorter and more questions were added to break things up. In most recent times, every question has started to come with a less than a minute answer, simpler vocabulary, little hard facts or statistics etc. These changes map very well to changes in the depth at which people were able to think due to the primary information source they were using. There is a good reason why reading is still seen as the most effective form of deep learning despite technological advancement. Because it is.