Goblins are terrible in combat, of course.
Trappers set traps, which can effectively stop even powerful units like Fury, at least for one turn.
Magic Disruption is also very useful in certain situations... You can, for example, deprive Raise Dead of its Lich, or do something else.
And even if they deal a lot of damage, it's still significant.
So, in my opinion, goblins may not be the best, but they can definitely beat peasants.
