There are a lot of guys who have never shot either cartridge, who assume .357 is the obvious or only real choice. “Versatility.” “Magnum power.” “Best man-stopping round ever” etc.
Those who have shot both realize that the .38spl will do about everything you need unless you have a habit of shooting through the steel door panels of stoutly built 1930s-60s American automobiles, and will do so more cheaply, with less blast, less recoil, and in guns that are lighter.
So, put another way, if you’re going to shoot .38s out of your .357 almost exclusively, why not just buy a .38? And the .38 can be handloaded to nearly .357 levels if one is so inclined, since the revolvers are generally made identically. The only reason for the new chambering was to prevent one of these hot new .38s from blowing up an old gun made at the turn of the century which would not have the necessary metallurgy or heat treatment to withstand the higher pressures of a hot rodded .38spl.