I'm not at all sure they would do the job better or worse than the people who are doing it in the province.
I'm suggesting if you want to simplify it under one umbrella, it makes more sense to simplify it under the Canada Revenue Agency, where the systems are already in place, than it does to centralize under Revenu Québec, where all these systems would need to be built. All the processes would need to be put in place. All the staffing would need to be done. It's quite a transformation you're looking at to solve a pretty small problem in the scheme of things.
I think there are much better ways to go about simplifying taxes for the residents of Quebec that will be a lot less costly both to individuals and to the government, and will not run the risk of losing thousands of jobs at a time when these jobs are so very important.