A rejection of metaphysics and epistemology is proof of their necessity
People who reject metaphysics and epistemology cannot escape the two. Their rejection itself of these two branches of philosophy is by itself a metaphysical and epistemological position.
Some mystics argue that the inarticulation of certain experiences is proof that there is something indivisible that comes before form and language. They are monists. They claim this while at the same time rejecting metaphysics and epistemology. By doing so, they contradict themselves.