When Apple purchased the BootCamp Project and took it in house, they made the Tool to only run under Mac OSX.
The driver files can only be retrieved through the BootCamp process they are not distributed in any other way.
As far as I am aware there are separate driver collections for the following groups of models:
MacBook introduced in 2015 or later
MacBook Air introduced in 2012 or later
MacBook Pro introduced in 2012 or later
Mac mini introduced in 2012 or later
iMac introduced in 2012 or later1
iMac Pro (all models)
Mac Pro introduced in 2013 or later
There is no need to Install the Whole Windows OS each time though.
