I'm curious: if most of these companies go on to raise rounds by going through the proper channels, why bother focusing on the pitch and not just the demo? It s

I'm curious: if most of these companies go on to raise rounds by going through the proper channels, why bother focusing on the pitch and not just the demo? It seems to me that if these companies still have to pitch to individual investors anyway, why not use the current iteration of Demo Day as their "Elevator Pitch" deck to investors, and use Demo Day as a real day of demonstrations, the "sneak preview" of things to come to wet the mouths of investors before they hear the real pitch?