That's an interesting supposition, but probably doesn't apply in this case, because of the eras we live in. When Gadd was coming up, the drum world still had Rich, Williams, Bellson, Bonham, Roach and all 3 Jones' /Elvin, Joe, Philly Joe/ in their primes. Then if that wasn't enough, you had Cobham, DeJohnette and Lenny White making their initial push, Columby, Garibaldi and Seraphine anchoring rock horn bands we still talk about today, Purdie and Stubblefield turning the recording world on its head, and Carl Palmer essentially creating the prog rock agenda.
There are many, many great drummers out there now, but can we really say that the current competitive landscape is on a late 60s to mid 70s level? See, that's the era when Gadd not only entered the scene, but rose to its highest level, which to me makes the role reveral scenario with Mayer an uneven comparison. There is no way that the gap was big enough in that era to have created the kind of over the top hero worship you see now for one guy.
Yes, there are numerous technical phenoms out there now, but is innovation combined with skillset really on par with those times?
By the late 70s, Gadd had already been the drummer on numerous breakthrough recordings. And as great as Jojo Mayer is, his body of musical works has yet to come close to where Gadd was at a similar point in his career. We also sometimes forget that Mayer is already pushing 50, not exactly the true definition of a rising star.
Now does all that diminish who Mayer is as a drummer and a musician? No. I agree with those legions who make a case for him being one of the true greats of his era. But the situation is what it is.