twitter et al are « easy to use » now because we have been using them for years and years.

have you ever seen someone use twitter or facebook for the very first time? it’s fucking confounding.

« what am i supposed to do »
« following? why would i do that? »
« why can’t i get to your uncle’s photos »

usability isn’t a secret UX sauce. it’s years of acclimation and the formation of communities that can bootstrap that acclimation for each other.