YAGNI is usually about modularization, often in response to Java-style OOP obsession. Like you don't need to define some big protocol that's only ever going to have one implementation.
Well this is not the context I had in mind. I'm thinking of the many times I've had to break apart 3kloc react components to reuse some part just because someone decided modularity didn't matter
I mean YAGNI is usually about modularization in general, so yeah a React component would be included in that, it's not limited to just OOP. 3K loc is probably well beyond the point where it should've been split up.