So that people who have no intention to settle in Quebec are not able to apply without misrepresentation.
But, how many days do you think one should pass? Till you receive citizenship? What about someone who doesn't plan to obtain citizenship? May I ask what is your basis / any sources behind this reasoning?
I agree that people who want to live extremely risk free should avoid moving but I don't agree with the practice where "guidelines" to live risk-free are presented as rules you shouldn't break. People's lives are difficult as they are, we don't need to make them harder by adding more unnecessary restrictions.
I have seen people moving during citizenship process as that looks reasonably safe, but at the same time they had their reasons to move due to job or family etc.
But, ethically and practically if people moves right after getting PR through PNP then intent is always questionable during their next round of immigration process because province has nominated you for the skill or labour market gap you are fulfilling for them.
But, there is always a gray area, as you mentioned correctly it is written nowhere that we can't move after PR to other province.
So , even if you move after PR to other province then keep all the documents ready to proof your changed intent .