I just found this on CIC website regarding biometrics.
http://www.cic.gc.ca/english/helpcentre/questions-answers-by-topic.asp?top=19
It is written below.
If you’re from a country in Asia, Asia Pacific or the Americas and we received your application before December 31, 2018, you don’t need to give your biometrics, even if your application is still being processed.
I had submitted my application on 03 December 2018. Maybe that's why. But I am not sure if that's the actual case with me.