I’d say the main purpose of any kind of lock (meaning the weakest link all around your house - strong front door won’t help if the kitchen door to the patio is always unlocked) is to be less appealing to burglars than the next house. At least that is how it works in Germany: Burglars drive around in vans, typically in daylight, sometimes walk around houses, looking for opportunities. If they see a cracked window, or an easy to access balcony door without too much exposure, they’ll give it a go. If that balcony door (I lived in a flat with that setting) has a big iron grating installed in front of it, they’ll move on and look for another place to rob, not because they couldn’t maybe find out that the iron grating is not attached very well, but because it looks like too much effort to even invest the time to find out.