I agree with your basic idea, but suggest that arithmetic is one branch of mathematics, not something separate.
Granted in the broader conceptual idea of mathematics as a whole. But MOST people NEVER will study mathematics as a whole. They NEED to be able to do arithmetic not prove the fundamental theorem of counting. They NEED to be able to some basic algebra and some basic geometry.
The idea that some how you can get every one trained as a proof capable mathematician is just plain silliness. Rather like suggesting that because we know how to drive a car we should all be auto mechanics