If someone close to me started being that honest or more importantly submissive with me, the power imbalance would probably upset me much more than any truths exposed. I don't want to control my friends, I want them to challenge me and support me. Alternatively a sudden change like that without obvious submissiveness might make me rather suspicious of what they're hiding behind those little lies.

This is not to say there aren't radically honest people who aren't even a bit submissive. I haven't seen such people and they might be rather interesting, but I wouldn't introduce them to anyone else I know. One person I know pretends to be radically honest by telling all kinds of personal stuff even to strangers nobody in their right mind would expose, but is actually full of shit too.