Billions of people don't use todo list apps so they're useless; just remember what to do.
Billions of people don't use post-its apps so they're useless; just remember what you're going to write down.
Billions of people don't have cars; just walk.
You can dismiss any invention since industrial revolution with this logic.
You can justify the value of any ridiculous invention by comparing it to a world-changing invention.
Common internet tropes include both "look at this forgotten jar that's been in the back of my fridge since 1987" and "doesn't it suck how much food we waste in the modern world?"
Nearly every modern invention could be dismissed with this attitude. "Why do you need a typewriter? Just write on paper like the rest of the world does."
"Why do you need a notebook? Just remember everything like the rest of us do."
But suggesting "Why not just try remembering lol" isn't really a valid criticism of the process. What you said here is a real criticism that actually adds to the conversation.