I find Kotal to be the best case study for this discussion. Blood/ Sun God Kotal specifically. There are others, but this match up really shines. Kotal beats Sub Zero in almost every way on a "vanilla" level, from neutral tools, air attacks, speed/ movement, mix up, anti-air, all the way to damage. What SG/ BG Kotal does lack and SZ has is a good wake up/ reversal. But still he makes up for it, towering over the blue ninja man.
But what happens when you add ice clone?
Grandmaster Sub Zero vs. Sun God Kotal has been called the worst (if not the worst then one of the worst) match up(s) in all of MKX. That's a huge claim though, how could that happen when Kotal has so many glaring advantages over SZ? The variation system, using Grandmaster, takes all of Kotal's advantageous tools and dulls them significantly. Suddenly, Sub's tools are far better than Kotal's.
So I mean SZ doesn't "need" extra moves or specials. But sometimes, having them takes match ups that are 6-4 in an opponents favor and makes them 7:3 in ours. All it costs is a little mental effort.