I've used React as a server-side templating language on many projects small and large. The main feature that makes React great for rendering HTML is higher-order components. In my experience any project of sufficient complexity starts to get ugly with a "regular" templating language. React encourages composition of small isolated components, which tends to result in code that is easier to understand and maintain.
Admittedly this works best on projects that don't require a massively complex interactive front-end, like news sites[0] and data reporting tools. But at some point you can just choose to start hydrating the interactive components in the browser without changing your back-end setup at all.
Really everything is delivering HTML ... and maybe something else.
I was thinking in the simplest form as the person I was responding to seemed to be saying that just to do something ultra basic react was not something they liked.
Admittedly this works best on projects that don't require a massively complex interactive front-end, like news sites[0] and data reporting tools. But at some point you can just choose to start hydrating the interactive components in the browser without changing your back-end setup at all.
[0]: https://wildlyinaccurate.com/introducing-a-faster-bbc-news-f...