Among the many virtues the game of chess can teach to its players, the ability to choose the right move from seemingly infinite possibilities is, in the end, what separates amateurs from grandmasters. When every move ever played is known and accounted for, a huge opportunity arises: the opportunity to go "out of book" and into the wilderness of never played territory.
Leaving the trail most travelled is not a rebel's choice, nor is it a sign of past wisdom's decay, the trail itself is its own boundary and can't lead anywhere it has not already been. Choices are all we ever make, and their consequences must never be taken for granted.
"Out of book" is a possibility ever present in the choices we make and increasingly rare as the game draws to an end. It is not without luck that leaving the trail will lead directly to victory, but it is without leaving the trail that any luck will lead to stalemate.