This. A thousand times, this. Every time I read a post about someone who can't get a date on OKCupid I roll my eyes. Then again, I live in New York so the high population density makes it a usable site. Sure, men outnumber women and women get more messages than men — but that's how the real world works as well. I've approached far more women in bars than have approached me. I imagine this is true for everybody except for rock stars, celebrities, gorgeous people, (and introverts whose only experience would be the few times they are approached).
The only thing that online dating gets you is an opportunity to introduce yourself and, if it's a good service, to introduce yourself to someone who is likelier to be what you are looking for. It's not a magic get-a-date thing, just joining up doesn't guarantee a date, just like going out to a bar doesn't guarantee that you're going to walk out of it with a girl or a phone number.
Attractive people get more messages? Yes, of course.
The only girls on dating sites have baggage? No more than any other single girls (or guys) of their age. At least that's been my experience for the last year or so that I've been single again and dating.