I'd say the Simplex ushed in the era of 2 jockey wheels. Prior to the war, racers had an unrational fear of friction. They kept the gears low to keep the chainline straight and a single jockey wheel to keep the minimum amount touching the chain.

The TdF changed all of that. Racers now accepted the dual wheel approach. I think that is more innovative than the GS. The GS only improved on moving the dual jockey wheels from side to side. All the heavy lifting was done by the TdF.