Gentoo does not separate headers

I encountered this
" To obtain the headers for libxkbcommon in Gentoo, you simply need to install the x11-libs/libxkbcommon package.

Unlike Linux distributions like Debian or Ubuntu which split packages into runtime and development pairs (e.g., libxkbcommon-dev), Gentoo includes development headers (.h files) by default in its standard packages."

All I want is the development headers, not the whole library.
When I try to emerge libxkbcommon I get

So I need to install 9 X11 packages, just to get a few header files.
That is very poorly organised … Debian has separate packages for development header files… because, when compiling something you may need header files but not necessarily the library functions.

One would have trouble building a minimal distro with Gentoo … it forces installs of unwanted material.

This is because in the past everything about Gentoo was compiled from source by the user in the past. There was no sense in splitting of the headers when you’re going to need them anyway in the next step.

The reason all the binary based distributions can afford to split headers and binaries up is because they don’t need the headers to be there by default in the first place.

Yes , that makes sense.
I am trying to compile some external code, outside of portage, and it just wants a couple of header files, and I have to install whole packages to get them.
I think if it really mattered, I would copy the header files from elsewhere.