That's how it is in all sports: how to judge the 'best ever', a.k.a. GOAT. Usually one has to do it by comparing a person to those in his era, and see who is dominant. For example, in golf ball golf, with changes in equipment over the years, was Bobby Jones the best? Jack Nicklaus? Tiger Woods?
Baseball has the distinction of playing with exactly the same equipment since it started. The size of the baseball has not changed at all in nearly a century and a half of organized pro baseball. The field dimensions are roughly the same over all that era. So comparing players is easy.
In chess, the game has been the same since the late 1800s, but the availability of books, computers, etc. has changed the players. So who was best? J.R. Capablanca of the early 20th century, who didn't lose a game in nearly 25 years? Bobby Fischer, who won (without a draw) nineteen straight games against the world's best on his way to the World Title? Or Garry Kasparov? All dominated their competition of their eras.
In disc golf, Climo dominated on early equipment, but what was the sport itself at the time? Given the same equipment, would Tiger dominate Jack, or Jack dominate Tiger? Likewise, both in their prime with the best equipment, would Paul McBeth dominate Climo? I think he would. I think Climo was great, but just did not have the competition that McBeth has. IMHO Paul McBeth is to this point the 'best ever'. YMMV.