Moggi's social influence is everything as introductions can only happen in the social realm. It continues that all evidence I can find suggests that his work went unnoticed until Wadler pushed it into view. In other words, people came to learn about his work only because of Wadler making the introduction. Nobody, except where one may find it trying to be implied in https://news.ycombinator.com/item?id=48304692, has suggested Wadler invented monads. The OP clearly wrote "introduced", not "invented".