Let's take for example driving a car.
Anyone can be taught to drive a car. Some do it for fun, some for pleasure, some for necessity, and some choose not to do it at all.
Ok now lets take an extreme area of driving like Formula 1 (NASCAR if you prefer) and look at what these guys do to excel at their game. Sure it takes a lot of specialized training and tactics that would never work in real life situations. They do shady things like wrecking their opponents cars and sacrificing their own ability to finish, for a DNF on their rival just so the points board will still have them in the lead when the race is over, and boom they are champion. They are professionals in their field and they repeatedly prove themselves in competition.
But they all started from somewhere. They learned the basics first. They all had to go to the DMV , take driving tests, and learn how to not grind gears on a standard at some point in their lives. Everyone should know the basics when trying to conquer any endeavor. The basis of BJJ is self defense. That is what it was designed for. Just like getting from point A to point B is what automobiles were designed for.
Yes there are certain areas to everything in life that you can niche yourself into, but personally I think you miss out on a lot of what makes what you enjoy in life so much more enriched and interesting. The basics may not necessarily hurt your game, but I don't see how they could hurt either. Besides, I bet there isn't an F1 driver out there that doesn't know how to parallel park as well as pull 5 g's in a corner on the race track.
This analogy might not make any sense to anyone else but me, but I like it anyway.