"(T)he idea that your stockpile of AR-15s could do anything against US troops with actual artillery

[needledriver]

3. The upper example claims to show the futility

of private ownership of military style weapons against a military armed with "actual artillery".

The lower example shows the real world effect that the Taliban (mostly armed with hand carried weapons) has. They can control whether negotiations to end the war even happen!

The US has spent nearly a trillion dollars in Afghanistan since 2001, with "actual artillery" and aircraft, and drones, and missiles, and the entire panoply of modern war - yet the Taliban persist.

The search phrase you are looking for is "asymmetric warfare". Check it out. You may come to a clearer understanding how and why lightly armed forces can effectively resist a modern military.