Make "Follow this channel" the default setting.
Usual Microsoft lack of UI intuition.
Channels should be followed by default with the user unfollowing it if they wish.
Thank you for the feedback. Changing the default setting is under review by the feature team, and your feedback is very useful as they are evaluating.
I wish there was at least a user setting that let this happen. It's annoying that I get added to a team and if I forget to follow it I will miss out on a day or more of posts until I remember to follow it.
Barring that, they should default to opt-out
Channels now have their own notification settings but they're currently opt-in. They should recursively follow the notification settings for the Team, then the global settings.