I occasionally host a writers and illustrators morning tea at my house, including one this morning. There is no agenda, and it's not a crit group. There is no prerequisite publication history to limit attendance.
We talk about the industry and various projects. We talk about marketing and how to do it better. It would be challenging to measure 'outcomes' but it's always great fun. I think it's the sense that we're all doing the same thing, and that so many of our experiences are similar.
I like to think it's the writer and illustrator equivalent of gathering to sew a friendship quilt.