The first S&W DAs with swing out cylinders were introduced around 1896. The 38 Special with "white" powder probably came out right around the turn of the century but they were common in black powder probably all the way into the 20s.

I'm not implying they were built around black powder, but rather PRESSURES that were low, like black powder-level. The full transition to smokeless took quite a bit of time. It certainly wasn't overnight, but the 38 Special was never "hot rodded" until bigger guns became available.

S&W didn't even start heat treating their cylinders until something like the later teens.

Old K frames and Colt D-frames are not the biggest guns. Remember that in 1935 when Elmer Keith's turbo charged 38 was turned into the 357 Magnum, they put it into the massive N Frame revolvers. They counterbored the chambers and everything. There simply wasn't a cartridge in existence at that time that ran at those pressures, and they didn't know how the guns would react. Even with Keith's testing of the 38, it wasn't done until the 38/44 Heavy Duty came out in around 1930. There wasn't an "overbuilt" 38 Special until then that he could feel comfortable experimenting with.

It wasn't until 1955 that the 357 Magnum was introduced in the K-frame with the Combat Magnum (later the model 19). And of course, with those we even see some durability issues shooting full house magnum loads.