what if the person lacks the flexibility to do Taekwondo kicks?
Then, you'd be talking to me. Ha! 20 years in and 4 degrees later, and I put away all the flashy TKD kicking years ago as street-ineffective. Cool to watch, sure. Fantastic spectator Olympic sport, absolutely. Rules-driven and full of exploitable holes, you bet.
Any style can beat any other style. Anyone can get caught, just like anyone can get lucky.
These truths being self-evident to folks who have spent a few years in and around the fight game, certain things are real truth, however. The fighter who trains to fight, really, is a better fighter than the person who practices techniques but isn't actually in a fight won't do as well. This being said, the guy who trains and practices his/her stuff, even if not intending to get into a fight, ever, is way ahead than someone who has never trained (keep in mind, those folks who just go out and learn to fight the hard way, by doing it, are training...).
I've got this theory about fighting, physical conflict, whatever. The person who successfully applies his rule system to the other guy - while not allowing the reverse to take place, wins.
TKD guy wants you "over there" where he can unload that catalog of whipping, turning, smashingly feisty kick techniques and long-range hand striking they're known for. BTDT. Wrestler who is good gets past, slips, blocks or is just plain lucky ends up standing next to TKD guy and grabs him. Oops, no more long range, now you've got to have a tool in your bag to deal with this new problem. Issue is, wrestler already has that tool kit in his bag, and his "bag" is one of those rolling, professional mechanic style tool kits compared to the TKD guys pair of pliers. In this scenario, things are not going to go well for TKD guy.
But, we could just as easily flip-flop the roles, make it a hyped up collegiate wrestler out for a bash a geek night and Oops, he happens to pick on a skilled TKD guy (who has seen wrestling before, key point). Wrestler tries to close, TKD guy evades and sticks him with a simple kick or strike and lets him pass by, Ole! Wrestler (if as in my mental image of this story, loses his cool) and just goes nuts trying to get to the TKD guy, and IF the TKD guy is able to keep the slipping and distance (a key in every striking art) right where he wants it, and is also able to deliver energy on target, and continue to do so effectively, will eventually (it may only take one good technique) cause enough damage to end the situation, either by submission (I give up, take my ball and go home IS submission), or defeat.
So, to me, it's not style at all, it's practice.
Then, it's practice something else.