Are phones as crackable as they used to be? I remember reading stories about how if you leave your bluetooth on, you're basically leaving your phone wide open.

Are phones as crackable as they used to be? I remember reading stories about how if you leave your bluetooth on, you're basically leaving your phone wide open. These days though, most phones require four digit passcodes and what I assume are fail2ban-like features. Am I wrong to assume that, or does it not matter for other reasons? I know TV shows like Person of Interest use technology more as a plot device than as a display of possibility, but the idea of forced pairing was a thing at some point, wasn't it?