I doubt that. I would guess that it is quite typical that owner members have one or two listings per year, typically for their vacations. And I guess that sitters do more sits: the nomads, the remote workers, the retirees and probably also others, to get some value out of their membership fee.
THS does not release many figures but recently I saw some numbers. The average member uses THS only ten nights per year. Latest Member Numbers - #4 by pietkuip