The concept is 140 years our of date."
You might want to revise that date. I have several post WWI to pre-WWII S&W revolvers that do NOT prevent them from going off if the hammer is accidentally struck. Early Rugers also had this issue. And the Colt Single Action (SA) still can fire if the hammer is accidentally struck. In the case of the Colt SA, the change hasn't been made because those that buy Colt SA, don't want Colt to change it. I guess if you spend over a $1000 dollars for a piece of history, you don't want any change to be made.
I don’t carry a SAA revolver for self defense. I know about the revolvers without the hammer block sleeve. I like revolvers and have some I have carried, but the capacity does not come close to the 13-17 round capacity of semi-autos of recent manufacture that I have found to be reliable.