You guys have some valid points HOWEVER, you've obviously never run a 100 miler. Sort of impossible not to walk at some point. Heck most of the top 10 finishers walked at some point. Are they subpar? I hardly think so.
Tell that to Zach Bitter. Or Jon Olsen. Or Yiannis Kouros, Oleg Kharitonov, Don Ritchie, Denis Jalybin, or any other number of runners to clock sub 13 hour 100milers.
Maybe it's impossible to not walk some of the trail 100s with steep mountain climbs, but 100mi itself is not the factor that determines whether one *HAS* to walk.