There are very specific reasons why Canada wants a younger workforce. Young people generally have fewer health problems and will put lower strain on the healthcare system. They also have the greatest potential to start new families. In addition to all of that, they are net contributors to the welfare state. In a country like Canada, which has a universal healthcare system and an aging population, accepting old people as immigrants would be suicidal and would collapse the entire healthcare system and welfare state. If Canada wants to invite old people, it would have to abolish the welfare state and privatise healthcare.
You and I are talking about two different things. I didn't suggest to you that Canada should bring in all elderly immigrants. Assuming you're talking about retirees over the age of 65, I agree that such elderly people would load the healthcare system. But remember, Canada admits, numbers-wise, a lot more refugees than most much larger countries, e.g., the USA. In percentage terms, the number is humongous, and overall, in terms of cost and all government benefits, that is a bigger drain than skilled migration. I agree with you that 95% of the immigrants for run-of-the-mill jobs must be young and flexible. One example I often quote in my area is that in 2023, I still pay a lot of Java developers the same Toronto pay I remember from 2008. All this is possible because of immigration and, in particular, folks from Asia willing to take less than market pay (of course, this includes me), and the employers save a lot in the process.
What I tried to say yesterday is that certain roles, e.g., surgeons, start their careers only in their mid-to-late 30s and will have some 7-8 years of experience by their mid-40s. Hence, IRCC not having streamwise or role-wise cutoffs hurts those, and ultimately, Canada doesn't get the best of breed personnel in such roles. The USA gets the best doctors, scientists, and Information technology personnel because it does not have these age restrictions.
All those who wish come to Canada in those 5% jobs are well-paid, and I'm sure if given the option, those professionals will opt for private health and not even depend on Canada's public health, unlike the low-paid youngsters. In my case, I moved for my kids college, and I have another 20 years of my career remaining, even if I don't continue to earn at the same as my current level. But for sure, I will continue to earn above-average pay to support myself and my wife. I'm not here for healthcare or any other freebies the government might give to young low-income earners.