“Plans are useless, planning is everything.”
Agile means you can drop what you’re working on at the drop of a hat when you discover that something else is higher priority. It doesn’t mean you shouldn’t plan.
Aha and their ilk are basically fancy todo list apps. With any todo list, if you put too much stuff in there, you’re lying to yourself. That doesn’t mean you shouldn’t have a todo list.
Edit: people absolutely do put too much stuff in there though.