I wrote a few huge class component-based Apps in React and they were working like charm and were very maintainable even for junior programmers. A few days with Redux and development was as easy as in jQuery days.

Then we hired a few front-ends who started pushing functional components where possible as it became the new paradigm and recommended way of writing React apps. From my perspective there is absolutely no difference between class and functional components, class is a few lines longer and it's supposedly harder to test but I don't know exactly why because testing classes was never an issue.

A few months passed by and maintenance became a headache because suddenly functional component X, Y and Z needed lifecycle methods and those were only available in class components! But class components are bad, right? So let's update React and use newly introduced hooks.

Now instead of me and 2 juniors you need 10 seniors to maintain the apps, nobody knows what does what, it's a nightmare. Class based components and even everything redux-related is much easier to comprehend than small logic in hooks. It's extremely easy to write unmaintainable code with hooks.