std::move is totally unnecessary when returning from a function, and really gets into the realm of you -- the programmer -- trying to babysit things that you should leave to the compiler.
What happens when you std::move something out of a function that isn't a variable local to that function? You can say that you'll never write code like that, but what happens if you write code that's just fine, and then refactor it and absent-mindedly don't change the std::move. You'll have fun tracking that bug down.
The compiler, on the other hand, is mostly incapable of making these kinds of mistakes.
Also: Important to note that returning a local variable from a function does not necessarily create an rvalue or use move semantics.
See here.
