I actually don't know, I'm not huge into investing in cards. I'm mostly a collector of cards I like that are cheap sort of guy but with this technique you could hunt for the Charizard while more or less guaranteeing you'll at least break even, since you can sell the packs you know don't have anything instead of opening them.

I'm assuming this technique can be modified to work on modern packs too so it's only a matter of time till you can't guarantee that a pack hasn't been scanned for good cards. They can even scan unsealed boxes. Currently it's a bit unattainable for your average investor but any of the big players could easily afford it and get an advantage.

Here's a link for anyone interested.

According to my friend, people are into boxes because you get a certain amount of guaranteed rarity, or will just buy individual cards. People distrust packs for just these kinds of reasons