It also allows implementing a different display interface. For example Haiku OS has a compatibility layer: https://discuss.haiku-os.org/t/xlibe-an-xlib-x11-comp

It also allows implementing a different display interface. For example Haiku OS has a compatibility layer: https://discuss.haiku-os.org/t/xlibe-an-xlib-x11-compatibility-layer-for-haiku/11692 https://discuss.haiku-os.org/t/xlibe-an-xlib-x11-compatibili...