The general public (including the next victims) don't have a way to confirm if payment was made. ShinyHunters would have to choose between arguing publicly that they were not paid or not releasing the data to protect their own reputation...
I do think that the partial information problem relating to new entrants into this market is interesting though.
The number of potential threat actors with partial/no information but that might speculate based on grandiose visions of ransom or outdated history is high.
We see dumb attempts at real-world ransoms/extortion which don't get paid at a pretty high clip based on this kind of partial knowledge.
You'll probably get your data leaked anyways, potentially get compromised again (see Instructure situation) and end up in a way worse place if you just shut up and paid it, or let it leak normally.
If no one pays the ransoms, but people believe that large ransoms are paid-- you still have the crime.