People used that number to argue other people, like the pretender Trevor Hoffman.
Other closers were said to be better, based on any number of metrics, like number of innings pitched, or innings per save, and whathaveyou.
Other closers have been said to be his equal or the new Mo at random points in his career, like K-Rod, Gagne, Papelbon, Lidge, Foulke and so on.
The quest to unanimous, unwavering respect and admiration of who he is/what he does is littered with the bones of closers who flamed out, or were flashes in the pan, or couldn't sustain their efficacy. Since 1996, the other teams have literally gone through dozens of potential closers and hundreds of potential setup men and other relievers, looking to find what Yankees fans have watched stably for 16 years.
Death, taxes, #42. The LAST #42 for all-time.
Today, Mariano Rivera took the last argument for those that wish to name other names away.
Today, there is no other answer for "who is the best relief pitcher to ever play baseball".
It will be that way forever.