That's actually a valid method for creating fiberglass molds. Its viable for situations where easily replaceable lightweight panels are required. Or to just sell them.
I personally am contemplating making some over fender flares on mine (69 slant 6 car) here's an example (scraptona)
They rivet on, so it's easily reversible. It feels like these trends come and go. Also, my quarter panels are trashed and Mopar tax is real ...