Nobody was doing what Lars was doing. There were "better" drummers like Benante, but they were still playing very conventionally and straight forward. Lars' weird crash placements and chokes, playing over the bar, using empty space. He was brilliant. And like I said, he was the only one doing it, (besides Steve Zimmerman of Fates Warning who was doing it on another level entirely).
It influenced millions, and you can hear it in the playing of the best metal drummers who followed.
That's greatness.