I've said it before and I'll say it again. The Masters division is not so much an 'I'm too old and physically disabled to really do BJJ' division, it's the 'I'm 34 not 24 and I've got a family and bills and shit and can't train 4-5 hours a day 5-6x a week' division. Plenty of elite guys are competitive at adult Mundials and Pans well into their 30s, but those are mostly guys who have been pros for years and have never stopped training at a high level all the time. For those of us who were never at the highest level (or even close), the ground we'd have to make up to compete with those guys would necessitate throwing away everything else in our lives. And hopefully by the time you're in your early 30s you're reasonably well established in your chosen profession, very likely with significant family obligations. Physically I'm in about as good of shape as I was in my mid 20s other than healing slower, but now instead of having not much of schedule and a lot of free time I have several employees and strict deadlines at work, a wife, and hopes of starting a family in the near future. Every hour I spend at BJJ is time I'm taking away from those other things, so I only spend so much time on the mat. Even the 8 weeks I've been training fairly hard for Worlds (though still probably not half of what a guy like Keenan trains) it's taken a toll on my professional work, and my wife is getting really damn tired of me training all the time and always being too tired to go out on the weekends (and not wanting to since no drinking while in 'camp').
So basically, I'm doing OG worlds rather than the Mundials because I can't compete with serious adult competitors on training time, so I know I'm not going to be able to compete with them on the mat. But I think I probably won't be outworked by anyone at OG worlds, so at least in that sense the playing field is relatively level. I'm well aware it doesn't carry the same panache as Mundials, and it shouldn't. But that doesn't mean it's worthless, it's just a competition for slightly older true amateurs.
This. Add 2 kids to the mix, and this explains it pretty well for me.