Undergrads who do research generally aren't very good at research yet. A major reason is they either lack or don't fully understand the pre-reqs, which they progressively and cumulatively learn during undergrad. A student can be incredibly smart, but acquiring a strong rigorous math background will still take years.
I can see a committed and gifted student being able to get most of the pre-reqs for doctoral studies in America or Canada while in high school.
Anyone can try doing research, even undergrads who half-know the foundations. However, trying research doesn't mean you have the background to do great research or to succeed in a postgrad program.
Plenty of people in postgrad programs don't know the foundations. It's ok. You are there to learn.
Completely unfair to expect someone already doing research to slog out 4yrs of classes not furthering their career.