I am not so sure about sourcemaps being an adequate replacement. They are just one feature flag toggle away from disappearing at any given moment. All it takes is one over-zealous tech decision maker to make them disappear on a website. And I know the types that would rather turn it off to shave off a few kB from the delivery, instead of rethinking their choice of framework. Or someone suddenly thinking, that they need to "protect" (obfuscate) their frontend source code. Source maps are too easy to switch off.