It's a weird question. But it's how I know whether or not I can deliver value to that potential employee. At big companies, salary and benefits is usually the main "value" that they provide. So, in essence, they provide the higher comp package necessary to make up for the fact that an employee is not going to learn as much as they would at a smaller company. A small company or an early stage startup is full of opportunities to learn. If your goal is to start your own company someday, I can make sure you're leaning the things that will help you get there. If you want to be a race car driver, I don't have much for you.
Employment is a two-way agreement. It's true that employers have the upper hand because they typically represent 100% of that person's income. The employee, on the other hand, is 1/N of the workforce. Switching costs are also likely higher for the employee.
For many people, I would imagine that a transparent and honest assessment is preferred to a pretend make-believe world where we imagine that an employee will spend their entire career in one place.
But yes, I do encounter some disbelief that I am asking a real question and am hoping for a real answer.
I'm certainly curious what the community thinks is the right way to discuss a candidate's career after this job. We all know there will be a job after this job and an employee after this employee. Transparency... something that seems to be valued by people on this forum... would seem to require that we talk about it.