The idea, presumably, is not that an armed populace would win an all-out battle against the government in which the people fighting on behalf of the government

The idea, presumably, is not that an armed populace would win an all-out battle against the government in which the people fighting on behalf of the government are fully motivated and committed. A bee does not expect to kill a dog(or whatever) with its stinger. It is a deterrent. Now, I'm not saying that it is necessarily worth it for the population to be armed in this way. I don't know whether it is worth it. Maybe not? But the question is more complicated than "well obviously the government is going to be more armed, and therefore there is no point." .