I would suggest putting MAIN_FILES in the sidebar of Finder, that way no matter where it really lives, you’ll know it’s there in the side bar.
Consideration: if you move it out of Documents, it no longer syncs to the cloud (if you have that turned on). Could be a consideration for cross-device work, and as a pseudo-backup.
Thought: put things where you will look for them first when you need them. I don’t intend to be flippant, but that is the ultimate goal. I hang the dog leash in the front closet because that’s where I look for the dog leash. Same can be said for files.
This is what motivated my recent post trying to get some clarity on PARA.
I’ve also found Trickster to be very helpful, as it allows locating files and folders through a third dimension (time or “when”) (with folders providing access by “where”, and tags providing access by “what”).