Perfect World VR (213): Capture the Flag
There was no need to rely on others when their strength was enough to overwhelm the enemy from the start.
In fact, they saw it as more of a crutch for cadets that relied on it to excel than a boost that would help them succeed in their endeavors.
The problem crops up when only one is involved in a particular activity and the other is nowhere to be found. The worst-case scenario would be that they would become so good together that they won't be able to perform well without the other.
And the situation down there which was quite unpredictable, at any point, one of them could be killed off or rendered incapable of fighting any longer maybe by an injury that would end their Guardian careers in a flash.