Some guys get to the basket better than others, some are able to make more spectacular passes. Some are better shooters than others. But the vast majority of point guards are not score-first. Shooting guards, by and large, take that as their primary role. Very, very few PG's look to score before they pass. Because that's not typically their job.
We like to think of each player as purely an individual, but it's just not true. There's a reason that teams tend to look for particular kinds of players (I.E.- prototypical QB's, great big men, true point guards, etc.). Westbrook is the best option OKC has at the point, but that doesn't mean it's his natural position. He played the 2 at UCLA, and he plays the point like a 2 guard.
LeBron brings the ball up the floor a lot, too. That doesn't mean he's a point guard.