Not true. I've launched, gotten into Selfie mode, moved it away from me, taken selfies, recalled it, and hand landed it all without having the GO app on. You have to ensure the Spark sees your movements and acknowledges them with the blinking lights.
Now with all that said. I did have problems initially and I'm not sure if it was me or the Spark, but with zero changes, everything works the way it should the second time out. Initially mine would fly backwards to the "bye" position and just sit there. I couldn't get it to take pictures or return with the "Y" gesture. It would just hover there. I had to turn on my Go app and pilot it manually down. Again, I'm not sure if it was me and my gestures or what. But since then, its worked fine everytime...
You only need the Go App to put it in Gesture mode if everything is already turned on. I've done that before. Flown around then put it in gesture mode.