People have been dealing with garbage word processor programs, publishing editors, and even doing documents in vector graphics editors. Imagine using an editor that just uses HTML + CSS under the hood, it's not that far from proprietary XML formats. If these features were standard, one could create such an editor and allow its output to be viewed everywhere.

Besides, I think this is cool. Someone saw a problem and solved it. I think it looks better too. Now, if only italics were properly spaced from normal text... but that's available in CSS.