There are a lot of moving parts when comparing both leagues. NFL is a national TV product.
There is a distinction between having a high payroll and doing it smart in MLB vs signing Boras's big guys to dumb contracts. Harper seems to be working out for now, but usually it's a dumb way for a team to spend money, and doesn't necessarily bring success. Nor does whatever the Mets and Padres strategy of spending is. Yankees fans don't seem too comfortable that they'll even be able to keep Soto and he may well go to free agency.
Nats views are pretty skewed by the fact that we had so many high profile Boras guys come through. He has been successful in convincing his big guys to not place any value in early security to go all in for the big prize in free agency. It definitely works at a macro scale across his stable, but some individuals end up getting screwed. His approach takes away any leverage a team has for trying to keep his players long term.