I think it's nothing more complicated than an incredible level of inertia in "the Book" of strategy. The game today is vastly different from the one 150 years ago. First base was once considered a defense-first position, fielding errors were prevalent, the ball was softer, the athletes were part-timers who had other jobs in the off-season, sore-armed pitchers were a mystery that they tried to avoid by "pitching in the pinch". Slowly the game evolved, but the strategies remained entrenched - ground balls were still prized and an "uppercut" swing was generally derided as showboating. When someone like Bill James in the 1980s used evidence-based logic that walks, for instance, were undervalued, or that a certain percentage of fly balls were destined to go out, there was tremendous pushback from the old guard, even if he was merely reinforcing what some of that old guard (e.g. Earl Weaver) was saying. The ability to generate evidence now dwarfs what was available to James, and the strategies reflect that.