Those "peasant armies" that were un-tightening the US had access to machine guns, grenades, RPGs, unguided rockets, mortars, IEDs, surface-to-air missiles.
You're making a leap by saying that disarming is giving all power to the elite. The elite already have power, and guns in the hands of civilians are not actually power, they're the illusion of power.
Labor gave up their economic weapons (unions) because times were peaceful and prosperous
Not in France. France doesn't have a gun problem, but they have strong unions, and in France people are happy to use their power to hold strikes and force the government to acknowledge their demands.
Doing the same for guns and the government is rolling out the red carpet for the jackboots to break in because there is nothing to fear.
That's my point, there never was anything to fear for the rich. They don't fear guns in the hands of the people because they know that they're safe. They know a few AR-15s are not a threat to them. What's a threat is unions, taxes on the ultra-rich, limits on the use of money in politics, etc. Plus, as we've seen recently, even when there's a actual fascist taking power and trampling on people's civil liberties, people aren't actually going to use their guns.