Why is the .357 Sig lauded for its penetration potential for self defense? Won't carrying hollow points nullify penetration?

I've seen some opinions about why the 357 sig is good for self defense or concealed carry. Something along the lines of, it has amazing power and penetration ability. But self defense ammunition will be hollow points yes? So penetration, like through a car door or glass window or whatever, isn't going to be possible anyways?Do all hollowpoints, regardless of caliber, mitigate penetration? And you'd never carry full ball ammo for self defense cuz it'd just poke a small hole without a wound channel, and it'd overpenetrate and risk hitting bystanders (yes, know your background yada yada). via /r/CCW http://ift.tt/2hut0Aw