Mpv is the only misbehaving package: app-admin/eselect-1.4.6 (doc ? dev-python/docutils) dev-python/dbus-python-1.2.4 (doc ? dev-python/docutils[python_targets_python2_7?]) dev-python/pycrypto-2.6.1-r1 (doc ? dev-python/docutils[python_targets_python2_7(-)?,python_targets_python3_3(-)?,python_targets_python3_4(-)?,python_targets_python3_5(-)?,-python_single_target_python2_7(-),-python_single_target_python3_3(-),-python_single_target_python3_4(-),-python_single_target_python3_5(-)]) media-libs/lensfun-0.3.2 (doc ? dev-python/docutils) media-video/mpv-0.20.0 (dev-python/docutils)
docutils package is used to generate man pages. Man pages are an essential part of the mpv package and thus they don't belong under 'doc' USE. If you don't want docutils on your system you can safely remove it after mpv is built as docutils is required only during build. Example command to remove build-time deps: `emerge --depclean --with-bdeps=n`