I tend to agree with you. If for no other reason than (and yes, I know it's a cliche) no one changes a bad behavior until THEY'RE ready to own up to and change the behavior. Having even the best of friends TELL you that your behavior is bad and wrong isn't likely to do anything but piss you off. And in the case of a strong-willed person, just get their back up and make them even more determined to keep doing what they're doing, rather than suddenly admit that the behavior is bad.