even if you see they have dim shield, even if you see they have some sort of cc to stop your creatures cold, what can you do? you can't simply NOT play the creatures you're holding. Say you're running a mono 
deck using this card. Since you're against a rainbow, you scout any potential cc that could kill your dragons. Even if you see a lightning in their hand, you can't simply wait to play the dragon because the rainbow will outrush you. The only way for most decks to win is to do enough damage to bring the opponent's HP to zero. You can't hold onto creatures just because they'll kill it; you'll have to use the creature anyway.
That's why you would only put this in your deck if you can make use of it. For example, you run an earth-dark EQ domin deck and opponent has only 1 pillar and 1 pendulum out. If you can see they have more in hand, you simply wait until you can deal more pressure than just simply destroying an expendable quanta source.
Or you have a steal and you don't know if you would steal that hourglass the opponent played on turn 2 or have something more worth to steal later. Or if you see that the opponent has no permanents at all, you can start stealing his pillars.
Just build your deck strategy around it.
