To be honest, I'm not sure I agree with this analogy completely. I think it's very well-articulated and thought out but I feel it may be too theoretical of an example to categorically claim that FP+ will increase wait times. I think there are several variable left out of this equation that could account for change in the results.
One of which is the time in which the FP+ time is distributed at. If your FP+ is scheduled for an hour when the park is at its highest crowd level of the day, and (at least from our observations) CMs tend to favor FP to standby when allowing the guests to proceed to either the ride or further waiting area. If a ride is at its peak crowd level and FP people are being allowed through, naturally the line will either feel, or actually be, longer than if the stand-by simply continues to move.
Another variable is that the example above makes it seem as if the return time is a definitive, exact time, and not a window of time. FP is an hour window. If the 501st person in line (who 'cut' the line in the analogy) got a return time of 10am-11am, he could have returned anywhere between that period. Let's say the 502nd person got a return time of 10:05am-11:05am.
If the 502nd person decides to ride at 10:05am and the 501st person decides to ride at 11:00am, doesn't the 501st person essentially 'wait' longer to ride than the 502nd, but on his own terms?
And doesn't the amount of time it takes to ride in the FP line depend on:
1) the length of the queue itself (in terms of walking distance)
2) the amount of people in the FP line
3) the amount of people in the Stand-by line
If FP+ are distributed in 5 min intervals, which I think they are, essentially there is an opportunity for people with 12 different FP time windows to either decide to ride at the same time, disperse evenly, or a mix of both. But again this is all dependent on the individual's choice of when to ride in that time interval. I feel it's not so much about cutting as it is an individual's decision when to ride combined with other factors that you can't assume remain constant.
Like for instance. If you have a FP+ for Space Mountain from 8-9pm and you know the parade is on at 9 which means lines usually dissipate right beforehand and during the parade, you decide to use FP+ at 8:40 so that you can ride quickly as Stand-by starts to get smaller, then get right back on stand-by because the line is short. Two for the price of one!
But an inexperienced Disney traveler with the same time window might decide to use it at 8 when the Stand-by line is 60 mins or so. That person will have waited in line (not a theoretical line, but an actual line) longer than the fellow who used his FP at a different time.
You'd get two different reviews of FP+ from those two guests simply because they used their FP+ at different times.
I think over time we are going to get conflicting reviews based on these variables. I don't think we will see the unanimous decision for either FP+ makes lines shorter or longer. It will be a mix of both, I feel.
And to me, this seems like the old FP system, with the only difference being that you can schedule your FPs two months in advance. Which golly gee, Disney really provided a game-changer with that one! Now I can reserve my magic band, where I'm eating and now where and when i'm riding all at the same time...2 Billion Dollars well spent