There are big conventions with no housing board to coordinate the process, and the way it works is, as each hotel opens, it is filled up, but some of those reservations are "just in case" and then people have to try over and over to see if a hotel that filled earlier has any rooms now because of cancellations.
If you think it sounds like a fun system, try attending Dragon$Con in two years. Pretty sure you have already missed out on hotel rooms for the next one. Also, do some research as at least one very large host hotel gives priority to legacy customers, which means there is no availability for new people.
If the hotels bumped room rates, within the block, that might increase availability. That would let the market sort it out and not leave us stuck dealing with each hotel as it opens its system. If there were no limits, I doubt it would make many people happy, as "whatever the market will bear" will turn out to be quite a lot, but I doubt that small increases would reduce demand.