Agree with Faaarii.I think it only may delay the process so it is your choice.
I would prefer to give access and since my family member used that and his application for PGP was approved and completed with in an year so I will not take any chance that can delay the processing time (They are already sleeping at each step of the application).
better to give CRA access for piece of mind and avoid to fill out extra forms. Giving your CRA access to IRCC will save a lot of your time insense of determine your income for a particular year. There is no specific way to fill out your employment history questions so I prefer to give CRA access.