python3-module-numpy-1:1.13.3-alt2.1.1.x86_64

setuptools are understood to be tools/commands needed to prepare Python packages/distributions, but numpy depends on it:

[root@localhost .in]# rpm -e python3-module-setuptools
error: Failed dependencies:
	python3(setuptools.command.develop) < 0 is needed by (installed) python3-module-numpy-1:1.13.3-alt2.1.1.x86_64
	python3(setuptools.command.egg_info) < 0 is needed by (installed) python3-module-numpy-1:1.13.3-alt2.1.1.x86_64
[root@localhost .in]# 

Probably, most part of numpy can work without setuptools, it's not needed at runtime.

Could it be possible to put the setuptools-related part into a separate subpackage, so that the base system where numpy cam be used would be more flexible, i.e., without the need to have setuptools installed?

(setuptools can have other development/packaging deps not really needed at runtime; that's why they are undesirable as a dependency.)