I think that both of you are assuming an average computer-proficient person when making estimates of how hard it is for someone to learn to use a wiki. An average person in general, or an average computer-phobic person, could have a much harder time.

E.g. one of my friends, who's definitely quite intelligent but has issues with computers, did eventually learn to use wikis, but not before three or four different people had tried to teach them to her. (Or possibly she did learn them on each occasion but then completely forgot about them in the intervening time - I'm fuzzy on the details.)