This is a much more polished version of what I do, which is to keep a note (in Notes app) called Brain Dump, and I jot down anything that is cluttering my mind, which I hold on for fear of forgetting. Just the act of writing it down helps; it's a reassurance that it's ok to let go of those thoughts because they are saved elsewhere.

What I like with MonkeyMind is the minimal amount of friction involved, as well as automatic timestamp.