I suspect the author is reacting less to the decline of literature and cultural elitism specifically and more to the general decline of those critical thinking skills that you gain by engaging in difficult works. I actually don't think anyone needs to read all of "the classics" and there's no point gatekeeping "intelligence" behind Shakespeare. If you feel like you had your brain expanded through, I don't know, Marvel movies, then the more power to you, but the key is that you are able to actually reflect on the work instead of just saying "well that was fun."

What is happening, however, is that people are getting increasingly acclimated to consuming easily-digestible content because our lives are ruled by a couple of companies who make money off of your attention and the human brain struggles to sustain focus through friction, even though the way we actually learn and question our lives is through that difficulty. Unfortunately, social media isn't the only culprit because almost all media that gets sold suffers from forced participation in the attention economy, although social media is probably one of the worst culprits just because the form factor makes it so easy to consume brain-rotting content.

I guess all that to say, I think the problem is fundamentally structural and thus essentially bound to happen because of the way our society and economy is organized, so I'm not sure what there is to do about this. Maybe we can all collectively decide to power through the lack of dopamine and actively choose content that is more difficult but also more edifying to force the algorithms to optimize for something more substantive.