I think this is a much more complex topic than people are assuming.
My answer is... no way, most people do not have the qualities needed to achieve a Weckl-like level.
It is about so much more than practice time. Obviously, there is an aptitude / natural gift / "born with it" element to it all. But no one has really emphasized how that aptitude interacts with desire and attitude.
To say that "anybody could be Weckl if he just practiced as much as Weckl" is naive, and misses the point; a big part of the greatness IS the ability and determination and that certain ratio of qualities needed in order to have WANTED to practice as much as Weckl did. And aptitude has a huge impact on that. We tend to like what we're good at. We also tend to be good at the things we like. Both concepts have a place here, and they create a rare feedback loop. But someone without tremendous drumming and rhythmic aptitude... sooner or later that person is going to hit a point on his own individual learning curve, a block or whatever, and it's then not going to be as enjoyable for him. His desire to practice will be affected. He'll get sidetracked and become interested is something else.
And never-mind the totally obsessive element to all of this. How many people have the combination of personality traits, the single-mindedness, and the focus, to dedicate all of their time to drumming alone? Not many. Most of us are interested in many, many things, and have multiple hobbies. There is an emerging hypothesis in the sciences that people who are great at certain types of things (like sports or music) are, in a sense, victims of a kind of illness, almost. I'm surely not explaining it well, but these people were susceptible to obsessiveness in a way that most of us could never be. This is not necessarily a bad thing. The greats are just out towards the edges of several certain bell curves. (Again, I am certainly not critiquing them; I think we all should celebrate these people, and am glad we do. They are freaks of nature, in a sense, who share their gift with all of us.)
Another way to think of it is this: the most beautiful women, science has shown, are the ones with the highest number of average features. That's right, the ones with least number of deviations from the norm. What's exceptional about a model is not her abundance of "beautiful" features; it is her overwhelming abundance of average features that is, surprisingly, so very rare. Most of us have a big nose, or funky ears, or a weird hairline, or some other combo of deviations that keep us off those Paris fashion runways (I've got about 20, haha), but a few people are lucky, take care of themselves properly, and so on.... But it is that *accumulation of averages* that is at play.
The obvious parallel is that someone like Gadd or Weckl or whomever is, in a sense, freakish in his drumming beauty. There are multiple deviations or susceptibilities that exist that would side-track most people on the quest to be the best. Attitude, perseverance, etc. These guys, however, have a certain combination of traits that allow them be the best. Add in that freakish obsessiveness (which may also partially be a sum of those other traits), and then you've got yourself a world class drummer.
No way could anyone do it if only they "only" practiced as much. To me, the point is, few have the qualities needed in order to tolerate or even *want* to practice that much.
(This does not even get into the mysteries of groove, etc... like, why can Gadd play a quarter note groove, 8 notes on the drums per measure, and it makes anyone within earshot want to dance, and yet we all know of the drum chops monsters (who've practiced as much as Weckl) and yet lack this ability. Clearly, there is an innate, "tapped into something rare" aspect at work here.)