That’s not very true, unfortunately. Knocking allows someone to somewhat figure out if anyone is home, allows a person to gauge who is home (a man or a woman) and how easily the knocker can gauge overtaking them. Breaking in means the homeowner may have time to get a weapon and means the knocker will have to search for anyone home.
Getting them to come up to the door and see if they’re armed makes it easy if a person is looking for a victim. People just breaking in are usually hoping no one is home and just wants to rob the place.