No Replay: People get salty because of subjectivity of person.

Replay: People get salty because of subjectivity of technology/rules.

Result: Some people will always be salty.

Why: There is an underlying subjectivity in nature. Nature itself is probabilistic. There should be general agreement on rules of competition with the intention to minimize the degree of contention. The creation/modification of rules to have a higher/lower degree of precision should be measured by the degree of utility they provide in minimizing that contention, as well as degree of attractiveness to convince people to agree to compete with them.

That being said, I'd be more concerned about head injuries than I would be about Replay review for the NFL.