There is no single simple solution. Wiki, IRC, Mailing Lists, Discourse, and other methods all have various strengths and weaknesses. Each has drifted in and out of fashion over the years…and will again.
Historically, IRC has been preferred for Ubuntu meetings over various voice methods for three reasons: 1) It has a meeting-bot which handles agendas and archives, making administration super-easy, 2) Written English is often much easier than spoken for the many non-native speakers involved, and 3) IRC is a free (in both senses) method - no vendor lock-in or data hostaging.
That doesn’t mean IRC will always be the best choice for all meetings…just that it’s currently still a valid choice.
It’s important to distinguish between:
Initial recruiting which should indeed use whatever communication fads reach the largest audience.
- Ongoing coordination of a team which can use any common method that the team agrees upon.
- Team/Loco/community governance which must use an open, transparent, and archival method.
When talking about wiki, it’s important to distinguish between the wiki itself and the various teams that use and edit the wiki documentation. Teams have cycles, too. When teams are down, their wiki pages languish. When teams are up, their wiki pages sparkle. I have seen Discourse-using organizations run in the same cycles.