React is indeed a complex library. For simple apps where components are simple and stateless React is easy. When you have more complex apps where components manage their own state and you have to also update the stateful component from outside, that's when the complexity starts. If the data rendered by the component is large and can't be easily cloned then it gets even more complicated.

> solved with a simple template rendered in the backend

Or a simple template rendered in the frontend, see this demo, where no huge libs are used. Instead a 200-line lib is used to get the equivalent of stateless React components: https://github.com/wisercoder/eureka