I don't think I agree. Skyrim's greatest asset are its warriors, true. But the Empire is doing a LOT to downplay their significant weaknesses. This primarily relates to food supply, as Skyrim simply cannot grow enough crops to sustain itself. Its population grew after joining the Empire, because they received resources from all over Cyrodiil. They don't make a huge deal of this in the game, but it is mentioned every so often that Skyrim relies on those.
Add to that the fact that Hunters will tell you that the lands are actually controlled by feudal laws. The Jarls own all the game in their woods, which means hunting them is illegal. And if we are assuming that lessons learned from human history apply, it's definitely not safe to assume they would allow increased hunting in years where the crop was bad.
They are rich in lumber and ore, which makes for good trading material. Under the stability of the Empire, that allowed the population to swell (and become relatively prosperous). But if they are surrounded by the Dominion on all sides, that won't be an option--many people will starve.
Add in the fact that Winterhold used to be one of its most powerful Holds, but it's now a shell.
There are other issues too. Lack of food challenges their ability to maintain a standing army (the Stormcloak's lack of resources is pretty apparent next to the well-funded Imperial military).
One of the most important, imo, is the turn from magic. It was WAY more common in Skyrim when Tiber Septim was emperor. But magic has been stigmatized as a result of the Thalmor and the Oblivion crisis.
And that's a ridiculously huge reduction in their capability for war. Healing, support, recon work, heavy assault, etc. A trained mage is worth way more than the best warrior is from a logistics standpoint. They can, in an instant, switch from acting as a highly mobile (and potentially invisible) heavy artillery platform and move to the role of combat medic. They can erect shields around the base of command, bolster the morale of your troops (and depress the enemy), turn the enemy on itself, conjure additional allies, and make allies from the fallen on both sides. Etc.
I seriously doubt that Skyrim, with its huge lack of Mages, can actually counter the Dominion in any meaningful way. A single Mage can produce a massive fireball capable of wiping out multiple soldiers from long range, or a small group can work together to blast through some gates. No number of catapults will counter that.
Also note that the Voice used to be more common in Skyrim, too. They actually used to have schools that taught the Thu'um. So they can't even make up for it by their own skill in magic.
Sure, the Dragonborn is a huge asset. But I can't believe he/she'd be significant enough to turn the tide of battle if the Dominion actually invaded.
Anyways, you all are horrible, @#%^ed up people