Your head is full. Tasks, ideas, things you promised people, things you promised yourself, stuff you're worried about forgetting. It's all rattling around in there competing for attention. A brain dump is how you get it out - and a backlog is how you make it useful.
There's a version of productivity advice that puts everything on you. Build better habits, develop more discipline, try harder. And while habits matter, there's something that influences your behavior more reliably than any habit you could build: the environment you're in.
If your environment is working against you, all the willpower in the world is fighting uphill.
Everyone has tried a todo list. Most people have also abandoned one. The problem isn't the concept - it's how they're used. A todo list done right is one of the most powerful tools you have. Done wrong, it's just a guilt list that grows faster than you can check things off.