You are almost, but not quite, correct, but in a way that is still wrong. Like so many things, ADHD is just part of a natural spectrum of cognitive differences

You are almost, but not quite, correct, but in a way that is still wrong. Like so many things, ADHD is just part of a natural spectrum of cognitive differences. In the world that humans evolved to live in, the hunter gatherer world, it doesn't have as many disadvantages and it has some advantages. It's good to have diversity in populations, even in things like cognition. But in a modern industrial world it has a lot more disadvantages. And given that that's the world we live in, we have to acknowledge that reality. ADHD is very much an attention based system of cognition, but that's not really suited to the modern world particularly well. There are lots of things that people need to learn, and cognitive tasks that people need to perform, that still need to get done regardless of whether they are interesting or not. People with ADHD can develop coping skills or use drugs that make that much easier, but it's still necessary. It might not be 100% fair to call it a "disorder" so much as a kind of impedance mismatch with modern society, but the mismatch still exists and still needs to be addressed.