Most current shader languages are very close to C in terms of syntax and behavior and these are some of the worst aspects of C as a language. I guess they could have went with SPIR-V but generally a compilation step shouldn't be required in web standards.
Literally all of these are owned by big corporations (Apple, Microsoft, Sony) and made specifically for their proprietary gpu APIs. C++ is just a superset of C which doesn't fix syntax problems. Making an open source standard with a modern syntax is a better idea than picking a favorite corporation.
