In general you’re correct, it’s just that currently this is how the system is. Grid operators in general don’t want their grid to be destabilised by oversupply to the point where they will pay you take the energy of their hands. Yes, disconnecting excess panels from the system would solve the issue, except that for most farms or households that was never a concern and solar panel owners have no incentive to care, so companies are now trying to push what are essentially smart plugs to let the solar panels be turned on / off on demand.