Shouldn't marathoners stop talking about "pushing limits" and start using big data for consulting?

‌They should assign grades based on performance and allow people to challenge themselves to reach the next level.
Isn't it wrong to constantly tell people to "push their limits" as if you're squeezing water from a dry towel?
Marathon experts make money through consulting.
It doesn't make sense to expect people who are neither professionals nor semi-pros to run 2 hours 30 minutes,
or to have them struggle for 6 hours just to finish.
It's just not right, is it?
I wish marathon experts would provide diagnostics
and generate some revenue that way.