> wind power genuinely became too cheap to meter.

No, it didn’t. The grid must always be in balance. Wind power production can’t be ramped up or down as needed. Overproduction could cause a surge on the grid, that would in fact be a massive liability for the power company.

Power became free for those periods because it was the cheapest option for the producer.

Kind of how it happened when crude oil was trading at negative $57 per bbl. The contracts came with an obligation that was impossible to meet, thus it was easier to pay someone to take them off your hands.