The point is to make sure you understand what research really is and that you’re not using Hollywood or TV depictions as the guiding force behind your decision to commit to a career of research.
That 2 years is not necessarily 2 years of real research experience (I’m sure for many it includes some period of pure lab scut work) or 2 years towards your PhD since the vast majority of people change topics for their PhD. Also it’s probably not 2 years of full time work as the person is often attending classes and such, and it’s also often two different 1 year experiences.
It’s essentially the equivalent of a pre-med shadowing and doing clinical experience/volunteering. The time scale for research is very different from the time scale for a clinical encounter so you need a larger amount of time to get quality exposure.