The movie maybe. But that intro was basically divorced from the rest of the movie.
The intro suggested that stupid people having kids was the reason humanity started evolving backward. It invoked natural selection and "survival of the fittest."
The intro even labeled the low birth rate couple and high birthrate couple with IQ scores to illustrate this point.
You argue that that the movie attributes the stupidity of its world to societal shifts. It does. It does a great job laying out a progression from late stage capitalism to idiocracy.
But that just further highlights how unnecessary that intro was. The intro attributed the stupidity to something entirely different.
I mean... look at the number of people who still, to this day, believe Joe Biden has dementia.
He's an elderly man with a speech impediment, and anyone with reasoning skills could tell he's still lucid. But the right's centuries-long war against education has paid off, and now reasoning skills are scarce.
Plus, ever since TikTok, there are now millions of people who get their "news" from five-second clips / soundbites. So if your "message" can't be summed up in what is essentially two pages of a picture book, in a way that can be digested without critical thinking, you are no longer a viable candidate.
Put differently, the winner from now on is whoever better pulls the gullible vote.