Very good point. Here's the thing, 10thPJJ is a VERY specialized game, which is why (IMHO) Eddie prefers that guys have solid previous grappling experience before going into his system. Your learning Eddie's game, and his take on things. He's not teaching all of those fundamentals that Jean Jacques Machado taught him to get to that point, he's teaching his discoveries AFTER that. Plus you have to factor in that Eddie does what works *FOR HIM*. He can get away with alot of the flat on your back Jiu Jitsu because he can bend his legs into places that 95% of the BJJ community cant do.
If you've already got solid fundamentals (late blue, early purple), then learning some of that stuff wouldnt really hinder your game too bad, because you'd just be picking out the stuff that applies directly to you. Now learning Eddie's system as a day 1 white belt I think is bad IMO because there are quite a few areas that arent addressed, Half Guard retention being one of them. How many times have we seen top level BJJ guys attempting to use the Lockdown, only to get it smashed and passed.
The common rebuttal is "He just didnt get enough reps", but most of the guys dabbling with that stuff were ALREADY solid. So if you wanna learn 10thPJJ, thats fine, but just keep in mind that if you build a house with a weak foundation, it may look fine when the weather is pretty and clear, but soon as the storm comes, it'll crumble and fall apart.