Regarding child care/babysitting one's own grandchild as work or illegal work would be a particularly harsh interpretation of immigration law. I really don't see IRCC vigorously litigating such cases involving grandmas in federal court when the resources could be better used for stopping people who came to Canada solely to work and are actually getting paid while fraudulently working on visitor/ overstayed visas and thus blatantly breaking the law. No, it would not make any practical sense. Now, that does not in any way mean that parents and grandparents can stay in Canada on visitor visas endlessly, and I do agree with your earlier submissions that IRCC reserves the right to cancel visas/refuse applications if officers determine that by living in Canada for an extended period, a parent/grandparent no longer meets the criteria for the renewal of a visitor visa or the definition of a visitor.
Here's an excerpt from a letter to the HoC by no less a person than the Chair, Immigration Law Section of the Canadian Bar Association:
"Recent studies indicate that the net positive impact of the non-economic contributions of parents and grandparents on the economy,
including child care, assistance with family business activities, emotional support, cultural education, volunteerism, maintenance of social cohesion, and housekeeping – in addition to the financial resources they may contribute – is often overlooked."
Link to full letter here:
https://www.cba.org/CMSPages/GetFile.aspx?guid=14e53f42-575c-4d72-a305-f0755560f232
There are countless anecdotes of people actually stating childcare as the reason for inviting their PGPs to Canada in their (ultimately successful) visa applications.
I noticed that this issue has been discussed in the past:
https://www.canadavisa.com/canada-immigration-discussion-board/threads/sponsor-parent-family-class-who-has-overstayed.238145/
