That's how it works now, but I don't see why it has to be that way.
Take TSM. I've used a fastpass when the standby wait was about 30 minutes (back past Mr. Potatohead) and the FP lane was empty before the merge point. After merging, we were still behind many people who had been waiting in the standby line, and a few that had gone through the FP entrance. It took about 15 minutes to board. Wouldn't they want me to be out shopping for those 15 minutes?
Why not merge the lines closer to the front so I only had to wait in front of those with fastpass, and the corresponding ratio of standby riders?
I follow the reasoning behind increasing the FP distribution rate, but I don't understand why they haven't increased the FP/standby rider ratio to compensate. They're not doing anyone any favors by letting the FP line back up. They can only fit so many people on the ride each day (x number of standby riders, and x number of fastpass riders), and the loading rate is constant.
In my eyes, there is no reason to make FP riders wait in line for more than a couple of minutes.