hardwood floors and spikes

I have found the brass Audio Points and Coupling Disks sound great and protect my wooden floor.
http://www.audiopoints.com/

Linn "Skeets"

I use Nordost power points in titanium.
Not cheap but quite effective and virtually invisible

I just read one members suggestion about using pennies. I did the same thing but I had Hales Concept 3's (180 lbs) with three sharp cones each. They poked right through the pennies and left little impression of Abraham Lincoln on the wood floor. Pennies or nickels are fine for lighter speakers but try the brass coupling discs with felt on the bottom. If the speaker isn't too heavy you can even slide them on the floor without damage.

I always thought the point of spikes WAS to "drive" them into the flooring, in order to anchor the speakers securely. If that's the case, what's the point of putting the spikes on something hard, that the spikes can't penetrate? What am I missing here?