If we accept your premise, then we must accept that we all must take a beating without any recourse except fleeing if possible. That our right to defend ourselves consists solely of what we are able to do with the skills and strength we possess within ourselves. I don't agree.
First, a person whose intent to just 'whup' someone can find himself facing manslaughter after just one punch. It happens all too often that a simple fight results, unintentionally, in the death of another. Can one consider that when defending oneself?
Secondly, the underlying principle of self-defense and 'stand your ground' rests upon the premise that we don't have to choose between 'run or die'. We have, along with a right to be free from physical harm, a right to remain in the place we occupy without giving an inch to another who believes he/she has the right to use violent force to displace us.
I know liberals hate the idea. They would rather a person should just hand over their valuables to any who would demand them, submit to the physical assault or rape, or worse, and be grateful if one escapes with their life. But those days are soon coming to an end, as they should have long ago.