I feel like this is a complete misunderstanding of the threat model here. Keys are not "like passwords", because to use a key you need to physically go up to someone's door, whereas with a password, you can generally do so from a computer terminal anywhere in the world, potentially using anonymizing proxies.

If anyone in the world could anonymously try and open my doors and, if they succeeded, could steal my valuables, locks would have been found insecure a long time ago.

Yes, the author here doesn't know how to use lockpicks or a crowbar to break into a house. The author also has presumably never tried to steal something from a house. Houses are generally just secure enough that the casual passer-by can't easily get into them, but not secure enough that if you really wanted to you couldn't get in. Most people who pick locks will tell you that picking locks is not a particularly good way to break into a house to steal things because breaking into a house is easy when you don't mind destroying someone's property. If you're a criminal you don't need anything more sophisticated than a crowbar (and even then you might just walk around until you find a door that's not locked at all).

So sure, maybe this makes one particular attack marginally easier (not really all that much easier than it was before), but illicit key duplication is still not the weakest part of your physical security by a long shot, so I don't think there's anything to worry about.