as long as the distance it can move is the same
The shifter controls how much it moves/how much cable is pulled
The shifter controls how much cable is pulled, that’s true, but the mech ratio controls how this is translated into lateral movement of the jockey wheel, and this isn’t the same for 10 and 11spd mechs, so your statement isn’t quite true…
it’s all here http://blog.artscyclery.com/science-behind-the-magic/science-behind-the-magic-drivetrain-compatibility/
If you run a 10 shifter with a 11 mech then it’ll undershift slightly, (which may well still be okay in reality). Cable pull on a 10 shifter is 3.4 and the mech ratio on a 11 mech is 1.1, so the mech will move 3.4 x 1.1 = 3.74mm per shift, which is slightly less than the sprocket pitch for a 10spd cassette of 3.95mm. In my experience Shimano (factory) setups overshift a tad, so undershifting may actually improve things.