It's not just the opening

Openings go in and out of fashion, often for no other reason than they are simply regarded as "unfashionable". When Kasparov revived the Scotch Game at the highest level as an alternative to the Ruy Lopez, I remembered a quote by Svetozar Gligoric in his book on the 1972 Fischer v Spassky World Championship Match

By his magic wand he [Fischer] transformed the Sicilian Defence into an endgame of the Scotch Opening! Spassky could not believe his eyes when he realised what trap he had fallen into, applying an opening he never intended, even in a dream.

When I first read this words in the early 80's I thought is was pretty harsh, given that Gligoric never explained why an ending from the Scotch was such a bad idea.
Of course these days Grandmasters are a little more pragmatic, realising that the openings themselves may not be bad, as long as they are in the right hands. For example, when Alexander Morozevich burst on to the international scene with his 9.5/10 at the 1994 Lloyds Bank tournament, his choice of openings caused much debate. Probably the one game that caused commentators to exclaim "Hey, you can't do that!" was his round 5 win over English GM Mark Hebden.

Morozevich,A (2575) - Hebden,M (2520) [C22]
Lloyds Bank op London (6), 1994

1.e4 e5 2.d4 exd4 3.Qxd4 Nc6 4.Qe3 Nf6 5.Nc3 Bb4 6.Bd2 0-0 7.0-0-0 Re8 8.Qg3 d6 9.f3 Ne5 10.h4 c6 11.h5 d5 12.Nge2 Nc4 13.h6 g6 14.Bg5 Qb6 15.Na4 Qa5 16.Bxf6 Qxa4 17.Nc3 Bxc3 18.Bxc3 Ne3 19.b3 Qxa2 20.Rd2 Qa3+ 21.Bb2 Qe7 22.Be2 dxe4 23.fxe4 Qxe4 24.Qg5 Nd5 (D)
25.Rxd5 Qxd5 26.Qf6 Kf8 27.Bc4 1-0

So clearly it wasn't just the opening that determined the outcome of the game, it was also the player choosing it.