[blowski]

In the context of this discussion, 'self-publish' means you control your content and its distribution. In that sense, Twitter and Tumbler are not self-publishing, since they own the software and can do pretty much whatever they like with your content. Also, you can't just pick up your Tweets and move them all to Facebook while retaining the same URL, whereas you can do this moving from self-hosted WordPress to self-hosted Jekyll.

That said, I don't think it's become harder to self-publish, but it hasn't matched the progress made by services like Twitter.