I know that, but it's still not clear to me why they ask some for it but not others.
Considering the time it can take to get, I think that should be mentioned as part of the documents required at the start.
The reason I’m able to find out for this is that
Most of the people applied(Indians) have similar names and when the officers looks into directory they found individuals with similar names and it becomes difficult for them to make sure it is you.
For example
One of my friend name is abc singh
and there’s a guy in the records having some criminal record having name abc singh def.
The system shows different format for the name of guy having some criminal background like
abc singh def or abc singh or abc def.
So at this point officers want to verify your identity and for this purpose they request rcmp pcc because by getting your biometrics it is much easier for them and they can recognize you exactly who you are