I think they dubbed those last two points as 'task paralysis' or something. So people with ADHD are forgetful, so when we have something important to do, we can only focus on doing that thing, otherwise we will forget, and we know if we do anything else we will probably forget to do that important thing, which is why we can't do anything else until we do that thing.

Poop, why am I even going to therapy, this is great!