I could give a personal account. I represented a client once during the time when the age was going to be lowered to under 19, and we were frantically putting together her application for that, because her son simply fell into this arbitrary number of “over 19”. It neglects to consider the situation of families with children who are still undergoing post-secondary education, who are contributing to the family in a different way. It's still a young enough age that they still have huge potential to contribute to Canadian society. It's short-sighted to think that the cutoff at 19 is appropriate. It seems arbitrary, in essence, given the age group of people who are attending post-secondary education.
On October 20th, 2016. See this statement in context.