Here's one way to look at it...
The K-frame .357 Magnums got a reputation of durability issues (we've discussed a hundred billion times...) and it was enough for S&W to simply STOP making them, but at the same time... they never stopped building a .357 Magnum
J-frame and it just makes me wonder a bit if the J-frame magnums never showed the extreme wear because no (normal, rational) human would ever put that much .357 Magnum through a J-frame because it's obnoxious?!
In comparing my own tastes to
many folks I've known and shot with, I believe I can handle handgun recoil fairly well, perhaps better than the "average" gun owner. (nobody in these forums is the "average gun owner", btw) But I'll tell you, I don't find .44 Magnum enjoyable in almost
any platform and I don't know if I ever will.
And a 5-shot, non-lugged-barrel L-frame, I am
certain, will not make the .44 Magnum an easier pill to swallow for anyone who struggles with any manner of recoil.
Thus:
Maybe S&W is counting on the "durability" of these coming from the fact that there's only so many mailboxes you can punch with your hand at 50 MPH out of a car window.