Forging can result in a stronger part than casting, all other things being equal, for some part geometries.
But other things are rarely equal. Let's imagine you're an engineer designing a part. The forged part costs $100. You can cast it for $80, and for this particular part the cast part is weaker - unless you spend $10 on a stronger alloy. If you do, you get the same strength for $90. And there are a lot of other variables - how exotic you get in the heat treat, machining costs like how fast cutters wear, how careful you have to be about corner radii to prevent stress concentrations, ad nauseam.
In the end, it's the total performance and price that matter; you don't want to focus only on one of the variables.
BTW, I'm not claiming anything about the design or materials of Ruger v. Smith revolvers in particular; I don't know any of the specifics. I'm just pointing out that design is a complex problem.
But other things are rarely equal. Let's imagine you're an engineer designing a part. The forged part costs $100. You can cast it for $80, and for this particular part the cast part is weaker - unless you spend $10 on a stronger alloy. If you do, you get the same strength for $90. And there are a lot of other variables - how exotic you get in the heat treat, machining costs like how fast cutters wear, how careful you have to be about corner radii to prevent stress concentrations, ad nauseam.
In the end, it's the total performance and price that matter; you don't want to focus only on one of the variables.
BTW, I'm not claiming anything about the design or materials of Ruger v. Smith revolvers in particular; I don't know any of the specifics. I'm just pointing out that design is a complex problem.