In a combat or war-type situation, I can understand your point, but that's where my understanding begins and ends.There are several reasons your logic concerning firearms is flawed:
Rats & Cockroaches sometimes run in packs. A single-shot shotgun is totally inadequate in a defensive situation, unless the victim can guarantee only one adversary. A potential victim would be helpless after one shot. Same issue with bolt-action rifles - limited capacity of 2-5 rounds which is adequate for hunting. Also slow to reload, slow follow-up shots if needed & the excessive power needed for long-range hunting endangers neighbors.
A revolver is fine, but you are limited to 6-8 rounds. Why do you suppose police departments use semi-auto pistols now? 15-18 round capacity & much faster reload.
A law-abiding citizen is entitled to have all the edge he can get; after all, criminals have no limitations on their weapons.
They'll always be criminals in this world, and even in countries where guns don't exist or aren't the norm, there will be gun crimes, but I stand firm on my thoughts as to automatic and semi-auto weaponry, aside from killing, they serve no purpose in a well-adjusted society/country.