Right handed players batting left handed?

So if you look at all of the hall of fame players back in the dead ball era and a little past it they are all left handed hitters. Most of them are right handed throwers... I know batting left handed gives you an advantage these days, but back then with the pitching not what it is now, why would all these naturally right handed players bat left handed? Examples: shoeless Joe, Earl averill, richie ashburn, Zachary wheat, Ted Williams, Ty Cobb, Duke snider, Larry doby, earle combs, Fred Clarke, goose goslin, Mel ott, enos slaughter, Elmer flick.......I mean, they are all naturally right handed, so why do they all bat left handed???