An academic option with clear standards for each grade and with passing to the next grade only based on assessed competence would be extremely popular with at least a quarter of the parents in GTA!
It would be just as popular as French immersion if not more.

The popularity of French Immersion stems to a large degrees from the fact that it screens the students admitted into the program to be ready to learn and free of behavioral problems.
(In most boards students need a recommendation from the kinder garden or grade 1 teacher in order to be considered for French immersion plus there is a self-selection into the program to start with; if a child is already struggling it is less likely that his parents would want to sign him up for French immersion.)

This ensures that despite the watered down educational standards and teacher training in Ontario at least a larger percentage of the class time is spent learning.

FromEurope is correct but incomplete.  French Immersion students are also ‘filtered’ by the ability of their parents to hoof them across the city each morning and pick them up after school. 

The French Immersion program gives moderately wealthier parents an escape valve from catchment areas that trap the poor into awful schools.  Anyone can apply, wink wink, but only relatively well-off parents can chauffeur their kids.  For their darlings, it’s like an exclusive private school, no need to jostle shoulders with poor kids or immigrants.

Between specialty schools and after-school tutoring, middle-class students almost keep up with private school students.  As usual, the poor get poorer.