If he didn't create a technique he made it so well known that he was credited with creating it, or he did his own thing with it. Yeah that might have been people who tapped before him i.e. Brian May in Queen(listen to the solo in It's Late off the News Of the World album), Billy Gibbons
supposedly did a tap while playing in some bar in the ealry 70's
, Gibbons also did artifical harmonics which is well known, somebody mentioned the guy in Free did taps, Ace Freehly did some taps on the Kiss Alive album(interestingly enough after Gene Simmons recorded the VH demo, "pssst, hey Ace, I worked with this dude named Eddie, he was doing this..try it in your solo"), Jimmy Webster is the first officially known guy to tap http://www.touchstyle.com/webster.html
.... but if they did it and the majority of the population didn't see them do it or hear it...what's it worth? Allan Holdsworth
was very innovative in the 70's but let's face it, alot of people outside of muscians don't know who he is.
Eddie innovated on alot of fronts, single humbucker in a Strat style body, his tone, his rhythm playing and the three minute hard rock tune which many bands in the 80's to this day ripped off, the tapped harmonics, again people say there were other players before him that did tapped harmonics but I can't think of one that made it a trademark, the sliding harmonics(i.e. listen to the lick after the solo in Somebody Get Me A Doctor during the main lick or the end of Sucka In A Three Piece, you'll know when you hear it), the Mean Street technique(the bass slapping technique applied to guitar), the table tray technique(live 1984 solo), his phrasing which everybody ripped off or tried to, etc...his whammy bar work, yeah Hendrix used the bar as did others but Eddie brought it to a new level when he arrived on the scene, etc...You can say all you want this person did this and that in a bar in 1973 but the point is when you hear somebody else do this stuff you think...Eddie VH.
Above all he was a great songwriter not just a shredder. He's a musician not just a guitar player trying to be a musician. His ability to play amazing stuff and wrap a great tune around it is the key to his greatness.
Somebody once mentioned in an interview and it's very true, Eddie opened alot of doors and closed them behind him. Meaning he innovated and created new things but if somebody else plays the licks you know it's Eddie VH.