I find that slack channels generally can be less pedantic and people are more likely to ask "dumb" questions they would otherwise not bother with in an email.

I find that slack channels generally can be less pedantic and people are more likely to ask "dumb" questions they would otherwise not bother with in an email. Archives do the job, but being able to have a dedicated channel in a tool i'm using for ongoing communication is nice and I find it nice to pin certain posts to the channel for reference or newcomers. With that said my only arguments for a slack or "async" IM client is generally predicated on it being internal communication.