At the very least they cant understand the benefits of doing so. I think this is largely a cultural thing.
Most writers can understand using quotes to denote quoted text.
Most professional writers follow style and usage guides which are pretty darned strict on where the punctuation goes or what word choice they've got. And if you've ever read through a style guide, you realize that they'd get fired if they didn't. Right now I'm playing with looking for capitalized words and posessive apostrophes, and using that for identifying titles and authors within streamed text. Realize off the bat that semantic markup right now sucks. Nobody's doing it.