Here's my take on mil-spec; In a technical sense, yeah there are very few true mil-spec rifles out on the market. A few are out there, but not many. In a slightly less literal sense though, mil-spec generally means it is built with the same materials and performs to the same standard as the true military parts. And for ARs, there is some applications where a mil-spec rifle is a good thing. If you shoot a lot, don't shoot at very long ranges, don't want to mount high magnification optics, and do a lot of on-the-move shooting, then a mil-spec AR is a good fit. Now, I didn't say a Colt AR, I said a mil-spec AR.
The thing that gets some people bent out of shape over is, what if another company offers a product that spec'd the same level as a Colt, but is 20% cheaper? Is it possible that people can have the same shooting experience, for the same amount of time, but for less money? What if one or two parts are different, but everything else is the same, is that worth making a big deal about? What if, and this really muddies the water, the rifle performs better than the Colt, costs less, last just as long, and is made with parts that are completely different than what Colt offers? This is why you will rarely see someone advocate a Colt based on accuracy, longevity of the major parts, trigger pull, or factory options. The reality is there are a number of different ARs out there that will do the same as the Colt for less, or one or two specific things better than the Colt for less. Instead, as I said before, it is a random grab bag of reasons that the Colt is better, none of which make a difference when you are shooting the rifle.