This is about home defense, not taking out a body-armored soldier on some battlefield. It’s more likely you’d be up against more than one urban-intruder IN YOUR HOME or AT YOUR FRONT DOOR.
It mentioned Israel.
Body armor is not uncommon today.
Also, the idea of a target rich environment isn’t absurd. Think after Katrina, or LA 1992 (https://en.wikipedia.org/wiki/1992_Los_Angeles_riots)...
It just depends on the situation.
A shotgun is better for survival against a natural threat (more versatile).
556 is better in an apocalyptic scenario where society is breaking down (even though it might be regional/local and temporary).
The latter gets shrugged off, but it happens even here in the US. When things get bad enough, there won’t be any police as with Katrina. They will be worried about their own life and family.