The number of people who lead climb multipitch walls is much bigger than the number who can climb a single 5.14 pitch, even on a toprope in a gym.
Keep in mind that these climbers spend years relying on their gear and taking no shortage of falls. They trust themselves and their partners. I don't want to minimize the mental challenge here (I struggle with it when I lead climb in a gym, let alone "trad" outside with my own gear), but for climbers at this level with this much experience, the fear of falling is sufficiently small that they're thinking about the climb rather than the consequences of a misstep.
Climbing 5.14 pitches is a whole other story. Perfect technique isn't enough; you also need a perfect physique -- lean and muscular in all the right places -- and not muscular in the wrong places, because muscle is heavy. Conventional climbing wisdom is that persistent hard work can take a fit person a long way -- to about 5.12 or so -- but after that it comes down to genetics. I'm reasonably athletic, have been climbing on and off for over a decade, and multiple times per week for the last 18 months. I'll be ecstatic if I can ever do a single 5.13 pitch.