> because OOP is easier to understand and leads to more maintainable code

How is OOP easier to understand exactly?

If you are debugging the code that looks something like this:

    class Child extends Parent {

      launchRockets() {
        this.launch(this.rockets);
      }

      render() {
        this.score = this.getScore();
        return `<span>${this.score}</span>`;
      }
      
    }

How do you know which part of your code contains implementation of this.getScore method? How do you know which part of your code is responsible for the number of this.rockets and how many methods in how many classes can change it? How do you find out which part of your code is going to call the launchRockets method, and whether this will even be this class's method or one of its children's? How many hops across your codebase do you need to make to figure all this stuff out?

How is this style any simpler than functional?