This is one of those statistics that is both true and misleading. The masters series did not exist before 1990, and there was no Olympic Tennis until 1988 (it was discontinued in the 1920s I think....)
So while this does not detract from what Feds has done, which is incredible, but to hail him as the *ONLY* man to do it is facetious since the greats of the 50s, 60s, 70s, and 80s *couldn't* have done it even if they had the ability.
I agree, but comparisons could still be made. Did these greats in decades past reach the final of every tournament which was important in their own time? If so, that is equally good.