And you're way less likely to physically restrain.
A decently-developed 16yo male can basically hold an entire house hostage. If he's delinquent enough to call the dad's bluff on physicality, there's little more you can do to discipline or control him other than call the police. And most parents don't want to call the cops on their own kid. It's a bit of a Catch-22, one through which I lived as a youngster unfortunately.
And for the crowd that says, "Discipline that kid! Spank him as a little one, and he'd know! I could teach a kid like that how to behave! Not in MY house!": save it. It takes highly-trained professionals (like

) to deal with children like that...and most parents aren't so trained.
I guess I just kind of relate to the mom using mace. We had times in my house where things were on the verge of zero control with a raging 16 year old. My folks probably SHOULD have used mace a time or two.