Actually, the phrase is often used about people who are arrogant, conceited, abrasive or unlikable due to their egotism. It might be about someone who is bitter, but if so it's because they aren't getting their way. At least that's how I usually hear it.
As for that article explaining where it comes from, that doesn't really line up with the current usage at all. While idioms, phrases, can have literal meanings that explain the figurative meaning, sometimes the phrase develops so far from the original meaning over time that the link is lost. So the article explains it was likely that people would put chips of wood on their shoulders and dare someone else to knock it off in order to initiate a fight. If you really stretch you could see how it eventually maybe came to mean someone who starts fights all the time, and usually people who start a lot of fights are arrogant, and the meaning just changed.