yeah that's true, but there is old sports writers and probably old columns written about players, especially certain ones that were most likely shady.
i just know cocaine was used fairly openly and as a pick-me-up in the early 1900's.
and even if we aren't talking about stimulants/drugs, there is vaseline, tobacco juice/spit, pine-tar, sandpaper, chalk/powder, etc.
Then you throw in corrupt players with mob ties. Mob influence i would suspect was more prevalent back then.
Dimensions of the fields, travel conditions, medical advice and/or care or lack of, equipment, etc.
number of players and teams, how often you seen the same guys, how less some played because of war service, the lack of talent during war time for some with replacement players.
There are so many variables one could factor in it is absurd to try and penalize an era of players that were just doing what everyone else around them basically was doing.