Personally, I don't think that's a universal rule. Some things are easier and simpler with movement -- e.g., riding a moving bike is much easier than making a bike stay in place without moving. For cycling moving is the more basic and fundamental version and staying still is a more advanced skill.
Some things are simpler stationary, some things are simpler moving, some things neither is more basic, they're just different.
Of course, there are always going to be exceptions, but I don't think that really addresses the problem of pedagogy for most people.
With pedagogical discussions ithere's always someone who says "well this guy learned better the other way" - and they'd be right, in a way, because it's always possible to come up with a counter example of someone who learned was successful with a different pedagogy.
OTOH, if you're discussing what works best for the most people in the most cases - it's a different discussion.