It's generally agreed

That's my point. Mathematical proofs aren't generally agreed. They are agreed by everyone to logically follow from the definitions and axioms started with. Every single statement in a mathematical proof evaluates to true or false, and if you don't believe a mathematical proof, you can directly point to a statement that is false. Philosophical arguments are "generally agreed" upon until the tools to take them out of philosophy are developed, and then the philosophical arguments are discarded entirely.

Your same argument that mathematics can be discussed under philosophy can be used to argue that mathematics can be discussed under the framework of wild untethered speculation. Neither one is a convincing argument that philosophy or wild untethered speculation is useful.

This is why ethics has failed. It has been built on the unstable foundation of philosophy instead of on the solid foundation of mathematics.