"raw" email doesn't help much when someone new comes in to the project, and has no access to the previous emails. systems like these keep most of the ceremony

"raw" email doesn't help much when someone new comes in to the project, and has no access to the previous emails. systems like these keep most of the ceremony of emails, but provide historical access. Of course, you can set up email group systems with archiving and search in those, but... that's more work, now you may have multiple systems for people to have access to, etc. systems like this are logical extensions of the ceremony of email with some added benefits.