I think this is absolutely right on. But a smart recruiter would realize that some measurable chunk of endorsements are selected by people who have no clue as t

I think this is absolutely right on. But a smart recruiter would realize that some measurable chunk of endorsements are selected by people who have no clue as to your skill set or level of ability in that particular area -- people who, for example, logged in, saw four possible endorsements they could give people in their network at the top of their screen, were feeling beneficent that day, and clicked on all of them. Or someone who you just endorsed for a skill, and they see that you did, and want to endorse you for something but already endorsed you for the 10 skills you preloaded, and so they just pick the first thing LinkedIn recommends. Presumably LinkedIn has some algorithm by which they look at people with similar skill set groupings, and say ah, statistically most of the people with this set have these three additional skills, and then farm that out to your network to see who endorses it. New endorsements tweak the skill set, which feeds back into the algorithm. It's almost like a glorified, twisted game of The Game of Life.