Metaphysics can't even be a thing in a web of belief! It's more a box for a bunch of things, with a tag that says "Ooo". Unless you want to define it otherwise, or I'm more confused than I think I am. So the category only makes sense if you want to use it to describe your feelings for some given subject. Why would that be a good way to frame a field of study?

That's what I suspect is problem with metaphysics; not the things in the box, which are arbitrary, rather that the box messes up your filing system.