That's so dishonest, though. They're married to the logic board on the phone because it's an integral part of the security chain for the phone to verify that yo

That's so dishonest, though. They're married to the logic board on the phone because it's an integral part of the security chain for the phone to verify that your fingerprint matches the key that's in the Secure Enclave. If they didn't do that, there would be no way to verify that a third-party repair wasn't surreptitiously stealing your biometric data every time you used it. It's not done to prevent third parties from repairing it. It's done to prevent nefarious parties from compromising the security of the device.