For many people, I feel there is way too much concern about using the "correct" rock.
If you have soft acidic water that has little to no buffering, you got to be careful but if you have normal run of the mill PH and hardness, I think of it this way. Say if the water is 7.0 PH, for giggles and has some fair amount of GH/KH to resist moving the PH (buffering?), adding an alkaline rock may tend to push things toward higher PH and add a bit of hardness. But then when we add something like plants or a great big old hunk of wood, those will tend to soften and move the water toward acidic.
We try to keep a steady, natural situation in our tanks, in many cases. So out in the real world there is a constant change going on in the water. In the piney woods during dry periods the pine needles will drive the water softer and more acidic compared to other times. In the middle of the country where the dominant rock is limestone, any spring fed lake will go higher PH and harder when the springs are running full and swing lower during dry times where the leaves and vegetation are stronger.
The fish don't die during a drought nor when it rains a lot! Nature has provided for these swings through genetics.
If you have normal water, add normal rocks and wood, etc., the normal fish will be fine with it. If you keep unusual fish, plants, or other stuff, then you have unusual problems. But for many of us, blaming rocks or wood is an excuse for poor care rather than the true cause of fish death.