simple, because at the begging you are not there to smash people, you are there to learn, at least through white betl, no one gives a fuck about smashing other noobs.
you are giving that advice to a dude with 1 week of training, would he be able to power out an armlock form a white belt with a couple of months of training? yes, would he be able to power out from a blue belt about his size, not so sure. Using "his strength" will only be useful vs noobs, it will give him a false sense of achievement, it will only be detrimental to his progress.
Also, a noob does not know the difference or when to use his explosion strenght, its ok to use strenght to finish a hold or when its required, but a noob does not have the technique down yet, so its all strenght for nothing.
you say he will realize eventually, yeah no shit, but it will be way better to let him get a grasp of techniques before he starts hulking people around, and no I give 2 shits when someone comes and uses strenght or rolls hard, Ive been grappling for quite sometime and I dont care about tough rolls actually I look for them, but I do not like to see my white belts playing a rugby match on the mats while the should be rolling.