There is no conspiracy.
The simple fact is that it is a night departure out of Dubai (so you wake up before midnight) with almost 15 hrs flt time to DC (about 1:15 longer than JFK).
You arrive at the hotel mid morning and have about 21 hours before pick up.
So you have been awake almost 20 hours less the bit of rest (won't call it sleep) you had in the bunk and you have a decision to make!!
You want to sleep, but if you do you'll be up in 8 or 9 hours with 10-11 hours till pick up time - in order to operate another ULR back to DXB.
Or you can attempt to stay awake (and traipze around playing tourist as one poster criticized the crew for doing) for as long as possible so that you can sleep adequately for the flight back.
While doing this you are 8 hours out of your time zone. So in this block you have missed one goods night sleep (the departing night) and you lose the 2nd good night by trying to prepare for the next flight.
If you stay up at arrival and attempt to stay awake so that you can rest for 8 hours or so before wake up you flip to the back side of your time zone again and, like most crew seem to do, you wake up 3 or 4 hours before call time since it is day/wake time in DXB.
Either way you are tired.
Combine this with 90 hours months and I am sorry, but fatigue is an issue. It is not rocket science and basic logic should show it is a difficult flight.