I’m not too sure anyone has been advocating turning cadets into “pack horses” or “tortoises”.
AFAIK, most will go by “live out your bergen, fight out your webbing, survive out your smock” - which generally keeps cadets as light as possible. Goretex and warm kit in a daysack is a no brainer, although if a cadet has webbing and no daysack for whatever reason then it has to be in the webbing.
This is in the context also that few cadets so far will have actually fought from their webbing or even carried a rifle in the field.
The only things not mentioned that we encourage cadets to carry is a med kit and I’ve known cadets be told to carry a second water bottle in their daysack for drinks powders - so they always have fresh water available.