Reading this again, I really have to object. Obliterate is at its most powerful against solitary powerful units, e.g. opposing tech 3 units. Low tech swarms are the answer to obliterate. It’s either that, or not playing any units at all.
Your two opinions are not mutually exclusive. If you don’t have mass removal spells, Obliterate offers a good way to deal with swarms, being generally more effective than overpower and much more than standard attacks. On the other hand, if you face a unit with Obliterate and can’t get rid of it, you’ll want to have as many cheap stuff to throw away before you lose valuable units.
So I reckon that makes you both right !