It has, you just never noticed.
"An equatorial mount doesn't suffer from field rotation, assuming it is properly polar-aligned. This applies to any equatorial mount, including traditional equatorial mounts like the one shown here, and fork mounts on equatorial wedges.

This is because when an equatorial mount tracks an object across the sky, the telescope does not remain horizontal, the tube rotates. Observe this equatorially-mounted telescope closely, and note how the "top" of the tube changes as the scope moves across the sky."
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See how an equatorial mount causes its tube to rotate?
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Now imagine a picture of the moon attached to the front end of the telescope, a mirror of what you would see in the sky. What would it look like as the telescope moved? It would look like it rotated! What does an equatorially mounted telescope actually see when looking at the moon? A moon that doesn't rotate!