Okay, lets turn to syria for a quick glance on how well an armed country can wage war against a regular army... it turns out even with real military weapons delivered by outside powers these rebels are still pretty much no match for the syrian army.You seem to have missed the news where they took one city after another and where they blew up one building in Palmyra after the other... for fun, and unchallenged. Similar in Afghanistan too, by the way. Kundus is officially firm within the hands of rebels again (but of course Kundus was always their "home", so that's not anything new).
And would it have made a difference if every syrian citizen had a home-defense gun at home when the war broke outSame problem as in other countries (Afghanistan again). Not few people are either passively or actively supportive of the rebels. Not few people silently agree with what they do, too (even if they say otherwise). The biggest problem for the armed forces is (and was) not fighting the rebels, but finding them.
You can see that from what is happening in Germany right now where people who allegedly fled from Islam terror start riots and mass battles with knives and clubs hundreds against hundreds over the Qaran, or over a toilet key or over who is first in the waiting line for lunch. These are the very "every citizen" who aren't rebels that you named.
The recent SPIEGEL report (yesterday or day before yesterday on RTL) stated that in one of these (Kassel if I recall correctly, but could have been Hamburg), they used tear gas against the police who tried to intervene. It's quite difficult for me to get tear gas (or it would be, if I had any interest) -- where did they get it from? Have to wonder what other weapons these poor victims have in their backpacks as well. There was footage where they were attacking some paramedic too, so it's not limited to "between them". Clearly, if you are a victim who fled from violence and if you are against violence, attacking people who are trying to help you is just what you do.
(In the defense of the Syrians: They're not the main bad guys. Not few of these fights involve Pakistani and Albanians either one one side or on both. Of course there is no war in either Albania or Pakistan, none that I'm aware of anyway... so I'm puzzled how our government allows them to stay at all).