Of games and experiences
The ancient Zen question addresses this directly: "If a tree falls in the forest, and no one is there to hear it, does it make a sound?" [...] As designers, we don't really care about the tree and how it falls — we care only about the experience of hearing it. The tree is just a means to an end.
Jesse Schell, "The Art of Game Design"
The whole point of making a game is to create an experience for the player. A game without the player is just a fancily-arranged-but-pointless bunch of bytes; it's like it doesn't exist.
Playing a game is bringing it into existence.
Watching someone playing your game is being witness of the moment in which your game stops being just a bunch of bytes. It's very meaningful for anyone making games.