No one said anything about *damage* so I'm not sure where that came from. I'm talking wear. Brake wear in particular. The reason for heel-toe is to minimize how often and how far the engine drops below maximum-torque rpm through curves (where one spends the most inertial energy), hence never removing your heel from the accelerator so you can always modulate rpm to rev match when engaging lower gears while hard braking into a curve, all the while keeping the engine spinning at it's optimal rpm to minimize energy loss and have maximum power on tap for when it's time to accelerate again on the far side of the apex. For me that would mean driving at a near constant 8300 rpm (which I do at the track) but to suggest that running around town to pick up some milk screaming like a banshee at 8300 rpm won't 1) wear your vehicle sooner than a less frantic style of driving and 2) won't get your license revoked, well, then you have some wonderful roads, incompetent police and interesting physical laws in NZ.

But, hey, each to his own. It's your car.
Oh, and I disagree, the important part is rev matching.

If you don't match, all that energy is taken away from smooth, balanced, forward motion and tossed about among the corners of the car. Wasted. That can also break the tires loose if you're already near the limit of your grip on the road. And before you tell everyone h/t a better way to drive, take note that usually only sportscars have the pedals placed and designed to properly and comfortably h/t drive. The reason for that is h/t is primarily a racing technique. I couldn't do it in my Pathfinder. Feet just ain't that big.

To try to would be inviting disaster.
A better explanation than either Mobius or I provided...
Oh Heel Yes!
And ignore the *pedal* on the left in the diagrams, that's a deadpedal (fancy name for footrest) that's found in many sportscars (mine has one

) so you have some place to rest your left foot other than the clutch pedal. Also, you can see in the diagrams the little angled area on the inside of the accelerator to assist heel-toe driving. That's what I mean about it being easier to perform when it's designed into the car. One final thing (and I'm sure that site goes into it). it's not really heel-toe, it's heel-ball of foot when properly done.