Im not sure if the internet made anyone dumber. It is just early on the average idiot self selected out of internet usage and there wasn't as much corporate or advertising money it to be worth manipulating.

AI im not sure of because it generates so much slop and anyone not already deep into a topic or field are unlikely to be able to recognize what parts are useful and what parts are common misconceptions or hallucinations.

Search engines are certainly worse tho, the first 20 hits on certain topics these days are AI articles that lack the needed details in favor of verbose generalizations or have questionable figures that other slop makes difficult to verify.