As much as I despise LLMs (*Spits in Dirt*) this is Absolute Bullshit.
LLMs have not been around long enough to cause a cognitive decline.
1. Television.
2. Decline in quality of education.
3. My Opinion - People generally tend toward being Stupid*.
"In the UK, James Flynn himself showed that the average IQ of a 14-year-old dropped by more than two points between 1980 and 2008." I don't recall Massive LLMs being around in 2008. See how I can use *Reason*?
Television.