That's not a very good way to look at black belt, or even brown or maybe even purple, in context to BJJ. IMHO. That's a mindset carry over from karate, kung fu, TKD, etc., not sure about judo never trained it enough to know. It's very accurate for blue belt because there are some minimums you have to have all around for that level -- kind of like in wrestling you have to be able to sprawl and chain your singles and doubles together, etc.
when I did a seminar with Randy Couture in 2010 I got introduced to the art of smash and pass which was wild to me. I don't think they called it that back then, but it was very antithetical to my "get guard with underhooks" or "butterfly guard with underhooks and sweep" and "armbar-triangle-omoplata" guard attack sequence type of training that I had been taught at my school. Because we had very legit blue/purple belts wrecking competitions locally in CA (including winning absolutes) that were winning with a good guard, good sweeps, and good top side control. Guard passing was good enough, but not as good as their wins would indicate. We didn't have a great mount game either looking back, although we were very good at back taking and winning from there. Long story short, it depends on where you train on what you'll know/be good at once you get to blue belt and start moving on. You certainly will not have
mastered "all positions and techniques" at a belt level because that isn't how BJJ is taught or practiced in my experience. Hell, even once you get a blue belt, you just spend the next several years getting better at the basics as you sprinkle in some "cooler" stuff. Most of the black belts I've met are very good, but they are "masters" of very little, and typically only the specific things they love doing the most.
This also doesn't even touch on the fact that BJJ is about principles. Not techniques (such as, for instance, TKD). Somewhere I'm sure Danaher explains this eloquently, but long story short it really isn't about techniques. There's multiple lifetimes worth of techniques to master, it just isn't feasible.
Anyway, not to sound cantankerous with everyone, but a lot of these takes are just very off in left field. Let me get my spectacles and see what Conor's spider guard looks like before I sign off on a legit BJJ black belt getting handed out