Yes, this is your standard ‘overthinking-stargate’ post.
But given that the main rival to Jaffa and Goa’uld forces would traditionally be other Jaffa and Goa’uld, the primary (or secondary, second to policing civilians) threat would come from air assault and assorting air-support, given that Ha’tak could land, or bring gliders or both, and Al’kesh could show up independently of Ha’taks and gliders, you’d think that Jaffa would have ample air defenses. But as far as we’ve seen in the show, they don’t.
What would complete the setting in that regard? Should they have had some sort of MANPADs? The ring-threading round gliders seem like the obvious choice, but they do not apparently make them as they once did, for some reason.
Given the egotistical nature of the Goauld I wouldn’t put it past them to have a sort of “gentleman’s agreement” to keep war mostly ground based to help limit the ability of the jaffa to rebel. We never see any Goauld weaponry that can track its target for instance. Everything just shoots in a straight line until it hits something. They want “war” to be up close and messy to help control their subjects. Given that, air defense as we understand it would defeat the purpose of fighting in the first place for them.