This has been a practice for decades - the WTS tells JWs not to book at hotels that have not entered a pricing agreement with the WTS; JWs do whatever they want.
From what I recall being told is that the hotels will offer additional complimentary rooms which were then booked by people who were in the know - Elders™, HLC members, visiting GB, DOs and COs.
When I was still in my late teens, one hotel had "lost" our booking and gave the room to someone else, so they gave us a *suite* for the price that we booked and reserved with a deposit. Best hotel *suite* EVER. The following years, my dad reserved the same room for us. We weren't allowed to tell any of the Friends™ about this room.
It was one of the only things that was a perk for going to the DC.