Because context matters.
Holloway was a kid when they fought.
Dustin is a good win but he wasn't at his best at 145, and he mauling Conor twice after that kind of hurts his case.
Mendes was great and a consistent #2 during the Aldo years, but he rolled straight out of the couch to fight Conor.
Then he sniped Aldo which was probably the most amazing title win ever. But it's not enough to be in GOAT conversation when you leave the division without ever defending.
Conor's FW isn't even in the same ballpark as what Aldo, Volk and Max have done in the division.