Ppl made this same argument back in BFA, but they were sneaky about it. They’d refuse to group with the buyer so they couldn’t see the extras being proc’d. The crafter would then sell the extras on the AH with the buyer being none the wiser.
Extra procs should be the incentive the buyer needs to have you be their crafter, the same way that you’re going to choose a crafter with high inspiration to recraft your neck, so you don’t spend as much gold on mats.