I think it is just a terminology confusion.
Rat breeders pretty commonly refer to "chewers" and specifically mean ones that chew the plastic bins or water bottles. It is usually understood in feeder breedee contexts that that is the thing referred to. Not that the rats don't get to chew wood or food as lab blocks or chew to wear down their teeth.
I bought my starter rats from pet quality lines from a breeder who hasn't had a chewer or biter (biting a human and drawing blood or aggressive attempts to bite when babies are present) in 3+ years.
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