I think, the only reason you wouldn't share is if you were doing something questionable that you wouldn't want someone you know seeing . I don't do anything questionable so I don't think I should hide my account ;O;!
Haha, yeah, if you have a little too many mature content on your account, maybe it's best not to share with your parents or grandparents XD I think "G-rated" accounts do get a little more attention since it's good to view for most people's eyes anyway. That's what I think at least o3o
EDIT: Well... now that I think of it, there are some popular people that does not so G-rated content so idk XD