The "incapacitated" status makes it so that the enemy behaves as if it were incapacitated. So, for example, if you flashfreeze a goat's head, for those 2 seconds on "incap" debuff, if it does the headbutt move, it will behave as if you had incapped the horns for real.

Unfortunately, most mob incapacitated behaviors hardly make a difference, so it doesn't even matter. The effect is pretty obvious on the buffalo, so that's why it seems like that's all it's good for because functionally, that IS all it's good for, lol.