I Never ever used the prices in lodging list, and very seldom even the hotels. I always found better deal than convention price if hotel had availibility (In general group pricing is higher in travel industry than individual pricing), and many times there were much nicer hotels better located available in the area, for even lower rate. The latter with one additional bonus, less people looking how you would behave after convention day without your badge on. You really must seek your own personal benefit first.
Yes, organisation will receive some benefit from using the designated hotels for designated prices. It could be in form of monetary incentive, or amount of free rooms and free meal arrangements to organiser body can be related to room nights booked. In general the hotel industry have a problem when calculating reports for nights used, if you do not use the organisation dedicated fare, they are not able to relate your booking to this organisation. This applies even for corporate fares, there is always discrepancy in figures comparing hotel's and ie. TMC's reports as hotel sees only corporate rate bookings belonging to corporation, not if they use another rate. The reporting is basically based on usage of specific rate in hotels, not like in airline industry where code attached to booking relates it to corporation, not the rate used. If organisation is using third party organiser, like Travel Management Company to arrange these, these sales may add up in their yearly volume, enabling in overall lower transactional fees for their other travel arrangements. It's really not about "we wan't to stay loyal to our business partners" kind of thing, there are also other strings attached.