It's a very small percentage of people that would have anything left in their stomach one hour after a small to medium size meal. Obviously if you are one of those sensitive people you might want to allow a little more time, or could be you don't get enough fiber
The issue with eating so close to the start of a ride is more related to the impact on insulin levels that thwart the burning of fat. When I do long rides (say 400KM), I don't eat within 3 hours of the start because I want to primarily rely upon beta oxidation but I might need some fibre because I am full of ****, too.