Some conferences blockbook(contract with hotel) rooms for the expected number of delegates plus a releasable contingency of rooms,and required extras such as conference rooms, refreshments etc.
These extra facilities costs as such are averaged out across expected number of rooms, hence the higher nightly rate.
The averaged extra in could include other things such as rooms for conference organiser/speakers.

Conference is on the hook for nn rooms even if not booked so may need to insist all attendees must book their rooms through conference.
One way to do this is to include rooms in the conference attendance fees with conference then paying for your room, as no one will pay twice for a room by booking rooms separately too then.

If conference then later pays for your booked room out of your attendance fees, it is unlikely you receive HH points yourself on room rate. You should earn on any f+b incidentals still.


.... Of course some conferences do the opposite, set attendance fee to include all conference costs including meeting and hotel room costs etc of organisers/speakers, and let you book your own hotel direct, either at the conference hotel or some other hotel. If enough attendees are expected such conferences may also negotiate lower roomrates with local hotel for attendees to optionally use.