Too bad for people who don’t RSVP well in advance. The host knows that they’re catering to a smaller number of guests and can plan accordingly.
The Host pays the establishment on the day of the party, so you do not pay anything up front. The reservation deposit is simply what secures your spot at table on night of the event, hence why it’s important to RSVP well ahead before seats are sold or given away. There will be more than enough time for guests to send over their hosts with their food orders once they arrive, but if one arrives without attending to this step first then it’ll happen at their own risk as there will not be any guarantee that there will be space on our register left free.