Are you kidding me? Source maps allow you to debug preprocessed as well as minified code. This allows seamless integration of multiple languages into the same ecosystem, libraries, etc.
You develop a language that is sent to the client in plain text. Then you write a lot of code in it. Then you realize that with so much code, file transfers take too long. You write a utility to strip out spaces and comments, as well as change variable names so files are smaller. Okay, so now you have unreadable plaintext files. After juggling minified and unminified version of the same code for some years you realize that debugging like that sucks. You develop a new format that allows you to map minified and unminified files. This format requires support on the browser side, as well as in the minification utility, and it also requires the author of the minified library to provide you with two additional files. You declare victory and pat yourself on the back. The whole process only takes a few years.
Meanwhile, people debugged binaries for several decades before your language even been developed.
