Long ago, in an era without social media, the editors and publishers of books and magazine determined what we read for fiction and non-fiction. In one sense they controlled what we thought too or thought about, because we naturally think about things we read. It wasn't a monopoly of course. We were able to think about other things but they had a large influence.
The general reading public was the one check on this control. If we didn't like something, we didn't buy it and the publishers didn't make money. If we did, the cash poured in. This part is still true today but there are differences.
For example, because of self-publishing, publishers do not have while the control they had. Oh, they still control what is branded with their name but anyone can publish just about anything they want and get it out there. This, of course, makes it harder to know what is good and what is not. And yet some will argue the self-publishing is better because it is more democratic. Others will argue that in matters of taste democracy has no place.
Personally, I'm not sure I have an opinion. Sure, I like being able to publish my own stuff. But I really don't want a terrorist manifesto published where young impressionable people will read it. On the other hand, the tight control publishing houses once had is archaic. It does not allow new talent in and preserves the old order when innovation is really needed.
But I think my biggest concern is that self-publishing allows individual to set themselves up as tin-pot dictators. These situations arise when one or more people decides to publish an anthology or magazine and puts out a call for submissions. Suddenly they decide what goes in and what does not. My experience with this is that even stories that have been well received by readers are in fact rejected.
I just have to shake my head in wonder. I guess I'm going to put my faith in the reading public. Money talks and if they download, buy, and read my stuff, the tin-pot dictators can all go to hell.