Rishi, let's say french is not mandatory, do you really think they will give you the CSQ in the interview if you only spoke in english ? they can do many things to reduce your overall points starting with the adaptability points unless you are a hotshot doctor or have some very important major.
personally, i don't know anyone who got a CSQ by not being able to communicate in french. but you can find as much stories as you want on the internet.
anyway it is up to you to believe whatever you choose