Applied philosophy is not math.
Another way to look at it is asking why in biology leads you to chemistry, asking why in chemistry leads you to physics, and asking why in physics leads you to math. Asking why in math does not lead you to philosophy.
Applied logic is math.
It's helpful to split Philosophy into two over-arching conceptual umbrellas:
- Epistemology - "how do we know what is real/true?"
- Ontology - "what is reality/truth?"
Epistemology is the portion of philosophy that likely rubs you the wrong way: theology is founded on epistemology. That said, so are linguistics & Political Science. In addition, mathematical NOTATION is a subset of linguistics, albeit an especially strict one.
Logic, Algebra, &, not least of all, statistical-modeling are the spawn of ontology. Without the ontological sub-dicipline of metaphysics, there would be no mathematical innovation. Whether you think calculus was discovered or invented, it would never come about if Newton(/that-German-Guy) hadn't been considering metaphysics.
Metaphysics rests on the theory that our epistemological-mathematical-notation provides a linguistic analog sufficient to describe the items & phenomena we have thus-far discovered as a species.