Earlier quoted context omitted.
Having never tried rock climbing, I'm curious what the potential causes of catastrophic events would be on this kind of a climb (that would necessitate safety gear for most climbers in the first place)...pieces of rock that give out under a hand/foot, appendage slipping out of place, etc.?
Like you said, it's not uncommon for people's feet to slip out from under them. A big part of climbing is the friction your shoes have against the rock, but move around, reach for something, and angle of your foot against the rock changes, along with the friction, and zoosh: your foot slides off. The rock can break off ("chossy" climbs, Pinnacles is notorious for this), but that's a less common occurrence than Hollyw…
A doctor from our local hospital died from, as far as we can tell, exactly this while climbing Discovery Wall. He was an excellent climber, and was using appropriate gear. He just was in the wrong place at the wrong time, and his safety equipment wasn't enough.