Personally I actually get value from HN, there's plenty that is informative and useful here and I consider HN a discussion forum. Social media is more what I would term fb where the main point is about the social connections, instead of the discussion and learning the discussion implies, in my opinion.
As for concrete proposals .. it's a massive topic, and full of interdependent systems and feedback loops and it might be hubris if anyone says 'heres a single concrete proposal to address it all'.. but here's some thoughts more on identifying issues to address in the context of schools, and aligning the results of schooling to learning.
A natural process of learning, especially for children, is to copy an image/role model/idol and learn through imagining themselves as that role model.
What are the social aspirations, or role models, that children usually idolise in our current schools and society? Film stars, sports stars, super models, instagram 'influences' which are usually just models ..
Common themes amongst these: glamourous lives, big money, social capital.
Another common theme is accomplishment in those fields does not have a linear relationship to hard work, to learning, and to the cultivation of knowledge.
Instead it's about coolness, social gaming, and largely about genetic lottery of beauty or sporting ability - yes some hard work but that's not going to get you far without these other pre-requisites.
It's also about luck, so rewards are not linearly related to effort, thus the payoff for effort is very uncertain.
Actually accomplishment in those fields is mostly a winner takes all market environment, so most people can never find success, and the majority of people who realise that they can't ever succeed to their aspirations give up putting in effort, it's a cause of apathy.
So the mainstream kids who idolise mainstream 'stars' aren't incentivised to learn and apply themselves mentally, they are incentivised to try to be cool, play social games, preen themselves for physical beauty, and hope to heck they are lucky .. and the vast majority has to face the unhappy reality they will never be stars.
That's a problem. What if their role models were Einstein who had a talent for imagining and discovering interesting things about the world, even as he worked a mundane job as a clerk (in the patent office). What if social capital for the mainstream classes was accrued to people who worked hard and made sensible decisions and created useful things, instead of to playing social gaming and trying to look beautiful/rich/make other people jealous and 'influence'.
So I don't have a concrete proposal, or the 'answers', but (I think) at least this is asking some of the right questions!