Hypothesis: All dimensions provide protection uniquely

[AnthroHeart]

I think protection of the body is a misnomer, because it's an illusion anyway, so what's there to protect?

The other self is self, so it's a moot point saying you'll protect yourself from another self.

Hit the nail on the head.

I would relate this idea of protection to 'shells' or containers like the Matryoksha dolls. Each density contains and 'protects' the space of all the other densities. Just like how the skin protects the muscles and flesh, the muscles protect the organs, the organs protect cellular processes, which are protected by their cell membranes, etc. Take away any part of the chain and the whole system falls apart.

I've never had damage to the muscles, but I can imagine it would be more painful than a simple skin burn.