There’s a good analogy for this that you’ve probably seen before: Bad media is like junk food for our brains. It’s easy to consume, immediately satisfying, and addictive… except it’s much worse than that, because bad media can — and often does — reinforce groupthink and bias.
Paul Graham talks about this in his essay “What I’ve Learned from Hacker News”. On user-voted news sites like reddit and Medium, the biggest problem is that it doesn’t rank things based on quality, it ranks by popularity, which are often very different.
In other words, whatever gets the most upvotes/recommends/etc. the fastest is the “best”, which means the site’s content inevitably drifts towards things that are quick to view, easy to understand, and non-controversial… unless you come up with countermeasures to prevent this from happening. Medium has done a great job with this. Nearly everything I’ve read on this site has been worthwhile in that I learned something, exposed me to new ideas, or better yet, has challenged my perspectives and way of thinking.
I guess my real point is that anything you read that has a positive impact on your way of thinking is worth reading; it doesn’t matter whether it was an insightful reddit comment, or a well-written article on Medium.
That said, there’s no replacement for a good book, which is what I think Wil Wheaton is saying.