I think the problem is that there is no single way that OW is meant to be run - in fact we haven't even got rules for half the possibilities yet!

The game is about a squad of troopers with attached specialists. They start off as a fairly average squad but through the course of the game their exploits earn them a reputation as the go-to unit of the regiment and eventually they will find themselves able to become a veteran squad, or a command squad or whatever they want to become within the scope of the Imperial Guard. And as the IG features an almost infinite amount of men and uncountable variations in combat doctrines this basically means you can play/run the game however you want.
Some players might be fine with you simply telling them:

"your squad is to hold this barricade, other units are fighting in other areas but you can ignore that background action and focus on what i throw at you"

whilst others might prefer a more visceral:

"your platoon is to hold this barricade - the other squads in the platoon will each have their points to hold and you may need to assist them as required"

Ultimately it depends on how immersive you want your game to be, because even in an elite stormtrooper regiment there will be hundreds, if not thousands of men in a regiment and so simply having a half dozen player characters running around completely unsupported would completely break the immersion for me…