No, but they're very high-traffic and if the "this was a deliberately bad patch" message is sent off-list, only to the maintainer, things can go south pretty easily. Off-list messages are easy to miss on inboxes whose email is in MAINTAINERS and receive a lot of spam, you can email someone right as they're going on vacation and so on. That's one of the reasons why a lot of development happens on a mailing list.