I believe parent is saying that RSS became something publishers publishers did not prefer to Twitter, Facebook, and real-time search. Simple syndication might be preferable to users, but it is not for publishers.
Sure, but I don't see how that's a criticism of RSS? "Nobody uses it because users prefer it!" Besides it still drives e.g. podcasting; apparently those publishers are still making money.
Publishers of text, as a whole, do not prefer RSS to other options to serve the same purpose. That's not a criticism, just a comparison. It means that given the choice, which publishers mainly are, they opt for things that aren't RSS.
