For non-essential visitors entering Canada to go canoe-camping (‘discretionary travel’’ as they call it), I can’t see any situation where the quarantine plan would be an issue.

If CBSA doesn’t believe you’ve been vaccinated, they will stop you from entering. If they don’t believe the result of your Covid19 test, they will stop you from entering. If they give you a random instant test and you fail, they will prevent you from entering.

Or in any case, you yourself will choose not to enter, right? I mean,
Who in their right mind is going to come to the border and then ‘quarantine away’ the entirety of their vacation time in a motel?

Ridiculous. The quarantine plan was for people who were entering to stay, like new immigrants and international students, not short-term visitors.