I'm not ashamed to admit that a BRD once kicked my ass fooling around 1 on 1. If you have the ability to sleep your target, or otherwise stop them from attacking you, you have a strong chance to win the fight.
While FFXI in general was designed around team-based coordination, a little 1 on 1 duel is still fun for the typical Ballista fan. I've gained the most knowledge and experience, and shared more information with fellow players over the years through sparring sessions.
You can't be so closed-minded to believe that a game is designed a certain way and think that there's only one way you should play it. There is more than one way to appreciate what's been made available to us. It's up to you to choose how you want to do it. For us, we choose to play Ballista as it is unique, fun, interesting, challenging, and did I say fun? Ballista used to be the original way to test your mettle. The best way to show you know how to stay on top of the game in terms of skill, gear and shear desire for competition that didn't involve camping NMs or fighting over who had the bigger e-peen vs. an EXP mob (which, if you haven't realized this by now, really really really SUCKED, and it still does).