I think the tools for developing in C (and C++) for the web are still in the early stages. Emscripten doesn't have working source maps yet. It also doesn't have

I think the tools for developing in C (and C++) for the web are still in the early stages. Emscripten doesn't have working source maps yet. It also doesn't have support for dynamic linking anymore (since they've changed their backend). Also browser's don't have that many tools for testing C/C++ compiled code so most of the testing has to be done native using Linux tools first. It's also geared more towards porting existing code right now so the libraries are made to look like POSIX APIs (which are incomplete) rather than Web APIs. Also games seem to be the focus rather than websites.