What exactly are you implying , that IRCC has the time and resources to monitor the social media presence of every one of the few hundred thousand immigration applications PR,study,work and visitors received every year. Sure they may carry out random checks where there is any suspicion of fraud taking place but doubtful this is a common occurance for every single application IRCC hopefully has better things to do with their time.
Unless someone is trying to execute a fraudulent application , fake employment details, fake marriage , fake documents and so on then nothing to worry about.