The problem is there is a huge gap between a development react application and a production react application that is served to users with best security/operational processes. The own creators of CRA do not recommend it be used in production and isn't that the goal for most react developers, to put apps into production?
> No Configuration Required: You don't need to configure anything. A reasonably good configuration of both development and production builds is handled for you so you can focus on writing code.
Nowhere in the docs do I see phrases like "don't use this in production".
As for the math analogy: I'd say the difference is that many calc concepts do require understanding of algebra to grasp and use, whereas the only thing about React that _sorta_ implies knowledge of Babel is the JSX transform, which isn't a hard requirement to use React but is certainly the common preferred approach.
Again, I'm not at all saying that people _shouldn't_ learn how to set up build tool configs. I agree that's valuable knowledge to have. I'm just saying it shouldn't be a hard blocker for using React, and that React tutorials shouldn't have to spend half their time teaching unrelated build tools instead of React itself.
Nothing prevents you from still writing entire Babel and Webpack configs by hand if you want to, but it shouldn't be a prerequisite for actually using React (or any other framework).