I wonder why plumbing fixture gaskets are so often made of natural rubber or other apparently utterly crappy rubber. They tend to degrade quite badly and often

I wonder why plumbing fixture gaskets are so often made of natural rubber or other apparently utterly crappy rubber. They tend to degrade quite badly and often fail if they are disturbed if they’re not brand new. EPDM is slightly more expensive in bulk than natural rubber and would (I expect) last a lot longer. Yet even an EPDM garden hose washer seems to be rare.