Even if we like to feel nostalgic about them, the "good old days" produced some problematic revolvers. Just because they involved a lot more hand-controlled machine operations for the parts, and hand fitting, that doesn't necessarily mean it was always done well.
I've certainly owned my fair share of older S&W, Colt & Ruger revolvers that weren't exactly functioning at the high end of the optimal (hopeful) quality range. Some NIB older S&W's required repair, or at least corrections, before they'd work normally. Some of my older Rugers required repair, too.
I had enough opportunity to listen to a previous S&W and Colt revolver armorer complain about keeping oloder wheelguns running well (including some 70's vintage blued Pythons issued as service revolvers, especially if they'd been fired with a lot of Magnum loads, instead of +P qual ammo).
I've seen my fair share of older S&W revolvers that had rough fitting and finish inside (even if they had nice exterior finishes), or had been fitted at the ragged end of normal spec.
Nowadays we can benefit from some better metallurgy (and heat treating).
At least with the newer S&W revolvers they're offering a lifetime (to the original owner) warranty which includes free shipping.