"identical amount of control that you're surrendering."
Not at all. If you send me an email without me asking, there is no public effect. One example of how this is bad with groups is what if I happen to be on a job search and someone adds me to the "I steal office supplies from my employer and sell them on eBay" group. Let's say a prospective employer is a friend of a FB friend of mine and looks at my profile and sees this. Job offer gone.
Counterpoint: you can remove yourself from a Facebook group, you can't remove yourself from a webpage or mailing list that someone else has control of. How's this so terrible again?
Yes, it is as bad as it looks. If one person can add you to a group without your approval, that's bad.