Yves, I share your belief that the problem is not abuse, but people “tweeting out to a dark vortex and getting nothing in return.” However, I don’t believe it is because people don’t know how to “use” Twitter.
I think it is simply because no one reads Twitter in the first place. I know many people who tweet and almost none of them read their timelines regularly. Some state that they literally never read their timelines (even though they tweet themselves).
If you take even a cursory glance at your own statistics on Twitter, you’ll see that you are lucky if your impressions match 8% of your followers. Actual engagement with the content (looking at a photo, following a link, etc.) is about 10% of impressions. I.e., less than 1% of your followers will engage with any given tweet. When someone with thousands of followers retweets you, you see the statistics get even grimmer.
Twitter has really become a place for shameless self-promotion that nobody (understandably) wants to read. For those of us who wanted to use it to have a more personal, genuine experience, it is of very little use, but what value we can get from it comes from very carefully choosing who we follow, including a liberal use of the mute button, in order to trim our timelines into something that is actually pleasurable to read.