At some point, for some reason, people got it in their heads that quotation marks are used to express emphasis. I don't know who started it, or when, but it's caught on like wildfire. It's the only convention of the English language that I can think of that's perpetuated solely by the momentum of those who use it incorrectly. This is incredibly unfortunate, given the punctuation's much more established role as an indicator of irony. What these people don't seem to realize is that written communication is a very fickle thing, and its formatting is just as important as--if not entirely crucial to--the words themselves that are used. Be smart about what you write, and how you write it! The only other option is to look like a dummy.