It was about the medical system being overwhelmed, leading to more deaths than would be the case with a flatter curve.
I think there is a fair criticism about how the IHME modeled the need for ICU beds and ventilators.
They forecast deaths and applied a multiple to it to get ICU beds and ventilators. They got that multiple from the CDC. And should have been quicker to adjust it as the data came in.
But the reason the multiple came in lower is New York City hospitals (and something similar happened in Madrid) became very picky about who they admitted. This allowed them to husband resources. But it also resulted in a yuge number of people dying without being able to get to a hospital. The hospitals in New York City were overwhelmed. Excess deaths resulted from that. But statistically it did not manifest itself in running out of beds or ventilators. It manifested itself in people dying at home.