Or is it just something that an old grumpy grandpa, who probably is like "everything was better back in my days", would say?
By the way, I remember a decade ago when I went to a school and had to do an essay in Danish and one of the things that I could write an essay about was an article saying something like "young people nowadays are so unintelligent", and I remember feeling defensive like "that's not true". (I think I did write that essay, but I don't think I expressed why I thought otherwise. I can't remember what I wrote in that essay.)
So the thing about people saying these kinds of things is nothing new.
Reminds me also of when I was watching videos recorded in the 60's and the comments were talking about how people had better vocabulary, expressed themselves eloquently and also how they wish people were still this articulate.
I have a feeling that people would blame bad education in school and the internet (especially TikTok) for making young people less intelligent.
I know that my country has often talked about how pupils in my country fail in PISA tests. (I think it was also like this, when I was younger. And I actually wasn't doing the test because I think my teachers were concerned that I would not finish the test in time or something.)
The article that I was supposed to write an essay about di also say something like "Don't trust people under the age of 30." (because the writer of the article found those people unintelligent)
I am under the age of 30, but I have been told that I'm a smart person. (or at least, I often win in that one quiz game that I have played with some people)
But maybe I'm unintelligent because I had kinda bad grades in college and graduated with a C minus. (going to that college actually made me feel less confident in my intelligence, even though perhaps the reason behind the bad grades was because I was a bit lazy and sometimes didn't ask for help if I had problems)