Ok, granted at some point you might want to pass your build through Browserify and Babel. No worries, both of those things are one liners in bash.
On the other hand, if you spend most of your time trying to make your build process the holy grail of hot-reloading webpack ES2020 isomorphic madness then you're not going to get much real work done. No one told you to do that though, and you can't blame React either. But even that isn't complexity. It's just annoying setup stuff. Real complexity grows with the scope of your app.
Of course, if all you're building is a static web page then I can see just using some HTML and CSS. But if you want to work professionally as a web developer then you need to know javascript and at least one major framework. You can not stay employed as a "full stack dev" if all you do is write an a couple HTML and CSS files and serve them with python httpSimpleServer.