Java, JavaScript, and Ruby didn't do this, and yet they all have solid build and dependency management stories. Java and JavaScript have even managed to have multiple build and dependency management tools existing at once without there being fragmentation and ruin. So clearly, having those tools dictated by the language is not essential.

I'm not sure why C and C++ have such a bad story here. Some combination of greater intrinsic complexity (separate headers, underspecified source-object relationships, architecture dependency, zillions of build flags, etc), a longer history of idiosyncratic libraries which people still need to use, the oppressive presence of distro package managers, and C programmers just being gluttons for punishment, probably.