I have been working with React codebases exclusively since 2016, and the quality of the code I've inherited has always been atrocious when dealing with medium to large apps. If you're just making a todo list, sure, it's all fun and games, but I'm yet to see a real commercial or enterprise-grade React app that doesn't become a disorganized mess. There has not been a single exception. I kid you not, I worked on a few AngularJS projects back in the day that were easier to manage as they grew compared to most React ones, as many things that other frameworks handle for you under the hood or make straightforward to handle manually will require boilerplate in React, and because React model is "open" and not standardized, most developers won't do it as the React team intended compared with what the docs suggest.
As a rough estimate, I've probably worked with 50 different engineers (mostly senior) doing React code across 6-7 companies. I would estimate that at most, 5-10 of them truly knew how React worked and how to