This is big misconception. So the rule says that your biometric is valid for 10 years and it will be considered only if you renew your same status that you applied for previously when you gave biometric.
e.g: You provided Biometric for Open Work Permit in last 10 years then it will be valid for your renewal of Open Work Permit within 10 years of last biometric.
Since you have now applied for PR which will change your status from Open Work Permit to PR it requires fresh biometric which will be valid for next 10 years and you would not need to provide biometric when you renew your PR.