Tech ain't that deep - and that's a problem

Why is learning C so much more generally useful than learning React? What I mean by the last point is that learning C tends to develop skills that are useful in a lot of other parts of software and tech work: if you know how to write decent C, you'll have a much easier time of understanding PostgreSQL internals, for example, while if you've learned React, it's anyone's guess as to whether or not that'll actually improve your HTML skills, for example.