Here is the link:
https://www.ualberta.ca/international-student-services/travel-to-canada-during-covid/non-discretionary-travel-updates
The reasons aren’t lame. For example the time difference if was huge, forcing you to switch your day to night and vice versa, would be devastating and a threat to your overall health and wellbeing.
the website also states the following:
“When you enter Canada with a valid study permit or
a POE Letter of Introduction that approves you for a study permit, your entry is now considered “non-discretionary” or “essential.” Therefore, an “Essential to Travel” letter is no longer required.
If you want additional documentation confirming that your studies in Canada are non-discretionary to a third party (airlines, border services), refer to the following processes:”
What I understood that you shouldn’t request for such documents to enter, unless third parties require it.