Definitely being a specialist is fine, and a simple game plan will still work (GSP has won and defended the world title with a game plan based on two moves: the jab, and shooting a double as a punch counter) if executed well. I guess my point is that the game plan that Royce is saying a BJJ guy should use is not actually the one he or his family trains for. If they did, they'd spend a ton of time doing standing clinch work and working Judo/Greco style throws without the gi on...but they don't spend any time doing that, and the TD work is almost all non-live SD (at least from the 'pure'
Humaita schools I've trained with). Royce is venturing into TMA territory here if his point is that all the moves are there, you just aren't executing them well enough. The same can be said of any art, what sets the real applicable combat sports apart is training like you plan to fight and I don't think pure GJJ does that. The only area where their training resembles anything that might happen in a fight is after the fight is already on the ground. Not surprisingly, they're great there but pretty weak everywhere else.
I feel too that I should throw out what I always throw out in these 'GJJ purity in MMA' threads, which is Carlson/BTT. The BJJ based guys who had the most success over the years have always been the ones with strong TD games, dominant top pressure, and decent striking, good enough that opponents have to respect it. To me, that wrestle-jitsu that Sperry, Bustamante, Arona, etc developed in the early 2000s and used to great effect in PRIDE is still the template for applying BJJ in MMA against other guys who also have some grappling knowledge. I think to a large extent the resurgence of Maia (in addition to his weight cut) has been due to his development of really dominating standing grappling. Incidentally, he basically neutralized Fitch with a clinch/trip game, but it was far more developed than anything Royce ever had.