Up until the 90's, it's fair to say that perhaps a majority of the prevailing wisdom was that lifting weights was bad for baseball players and basketball players. It would make you stiffer, slower, and you'd lose the flexibility you need. It would wear out your joints and impact your ability to throw.
Many pro athletes smoked. They practiced the same diets that the average citizen ate. Recovery from training, playing, injuries and surgeries was in a different galaxy.
Players born after that grew up with coaches and trainers who know far better. They start training and conditioning and playing with more advanced competitors at a much younger age. I think it's always why we have to judge the players in the all-time consideration based on the era they played in.