I fully understand a 3rd party auditor avoiding writing OFI's. But the OP was discussing internal audits, and I think internal auditors issuing OFI's is perfectly fine.
I also agree that a nonconformity should not be reduced to an OFI in any audit - they are different. But I will sometimes not document a nonconformity if it is minor and isolated and immediately fixed. Or, if I document it, I won't issue a CAR if it is immediately fixed.