Whats with anti theft stereo?

I found out my dads 2005 honda crv exl awd (all luxury options) has a anti theft stereo? what the hell? whats the point of having alarm if someone just tries to steal your stereo that probably needs a push from the back (you have to open the hood and push to get it out to inside) why not an alarm that goes off if someone broke a window or tried to steal the car? im just wondering whats with that.