The problem with a sim is that it won't see things like, how you're approach to the runway is too fast, or too slow, or how you need to use right (or left) rudder to keep it centered on the runway in a crosswind. And it certainly won't explain how and why we do those things.

A sim won't tell you how to do a stall turn, or to add down elevator in a slow roll to keep the plane from diving for the ground. Sure, you might eventually figure it out, but you're more likely to try and do the roll faster to keep it from diving. In the long run you'll end up learning bad habits, and never really learn the right way to control your plane.

It will likely keep you from destroying 3 or 4 planes in the learning process, you may only destroy 1 or 2.

A sim will not show you how to set up your servos, control horns and clevises, or how to tune or break in an engine, or keep your fingers out of the prop. It won't explain how to repair crash damage, or easier ways to cover, or install components.

I could go on, but you get the idea.
Dennis-