looking at the file list for xorgproto, i cannot understand how libx11 requires it (beyond make): it's all headers and pkgconfig..
they seemed to, briefly, get it right, then went all silly again...
ah , not silly but
pragmatic apparently ..
https://lists.archlinux.org/pipermail/arch-dev-public/2019-December/029767.html
so, if you force removed xorgproto or rebuilt libx11 with an adjusted pkgbuild, it would not actually break any runtime process .. just some headers might shed a tear over some other header not being around..
to his credit, Andreas, doesn't like it.. but it is the path of least effort, apparently..