Above you see the ill-tempered answer. I'll try and explain it without the profanity!
The technique has its benefits. Its as you implied a penetrating technique. Though its benefits can definitely be outweighed by its potential deterents.
Positively. The technique can be used to strike at the diaphram(under the ribcage), or the stomach, liver or kidneys. It can also(as Cussy McDrunkerson, I kid of course, said above) can be used to strike the throat.
Negatively. If you hit a solid bone, or even dense muscle such as the thighs, arms, or any other thickly developed musculature, you are as likely to damage your fingers as you are to cause an insignificant injury to your opponent, assuming you strike an area listed in this section.
All in all, its an effective self-defense technique, however it isn't one that you can open with. If your opponent has even a marginally relevant guard, you'll end up hitting an arm, or a skull, or some other larger denser piece of anatomy. While a skull hit may be very damaging to an opponent, comparative to a palm, or fist strike to the same area, you're far more likely to damage your hand or break your fingers with the technique you're describing.
Sig courtesy of that photo-matic magician limba
I went out the way that I fight. I went out on my shield. Thatís it. Done. --Chuck Liddell
My goal is to end my opponent --Carlos Condit