Another thing Tycho mentions (and that makes it into the comic today, NSFW) is that even for people familiar but not fanatic about the game like them, entering these tournaments can be really tough -- there are tons of solid decks and strategies out there, and if you haven't done the research, someone who has can very easily trounce you. They even mention a "three card infinite damage combo" that players can use. Unfortunately, that's way too far over my TCG strategy head to actually tell you what it is (maybe commenters can help), but it seems like for new players especially, these formal TCG events might be a little tough to get into.
Still, the Darkmoon Faire events are fun, even if you're not playing at the top of the heap. UDE has lots more news about upcoming events on their website.