I categorically disagree with this. Look at the enormous damage small groups of armed people have imparted on the government even recently. Two delusional guys in Boston shut down the entire city for multiple days and necessitated a state-wide response by blowing up a few pipe bombs, killing a police officer, and going on a car chase. This response cost millions and millions of dollars and resulted in millions of dollars more in lost productivity. The Waco Texas debacle necessitated a huge federal response which we are still feeling the effects of to this day. The Oklahoma City bombing was perpetrated by two guys who didn't even use firearms.

I'm certainly not endorsing any of these actions and I believe the government responses were warranted, but there is a clear history of rebellious armed civilian groups being huge problems for governments.