In fact, there's no scientific consensus research-wise on whether writing things by hand actually helps in any way.

Anecdotally, it never helped me to remember the stuff I was writing down.

Same.

While writting I think there's a very fine line that separates external storage from memorization. What I mean by this is that sometime we write ideas so we can avoid forgetting and be able to come back them (David Lynch), or as we write and develop a thought or subject, we are actually creating memories.

I think the point of writing stuff down is mainly organization, storage and exploration and not a memory exercise.