If you log in as the invited, you'll be shocked by the fact that the invitee can change everything, I mean everything, to the account. Even worse, they can deny your access to the account by a single click! Crazy!
It's like I'm the host and I invite guests to my home. The guests not only can change my wallpaper, flooring freely, but also can kick me out of my own home and take my house over to their possession. How absurd is that!
I don't know why Google has this arrangement. Maybe I'm not as smart as Google's high IQ people. :(