Generally in US or Canada, parents are not considiered as part of an adult child's immediate family. Try claiming your parents to your work extended insurnace, or taking them to your work party that welcome "family" to join. That's a cultural difference that's not what IRCC alone is considering.
Canadian born citizens don't have a choice, they are in Canada (not all of them have parents in Canada, e.g. birth tourisim). Naturalized citizens have a choice, they choose to immigrate to a Canada. It's a major choice in ones life. I think 20 years ago, not as many people applied to bring their parents here. It's the number of application and the extremly long processing time for these applications that leaded to an attempt for solutions (e.g. limited applications first come first served with cut off, then lottery...etc)