Entirely speculation, but one reason I can imagine is that if everyone is sick at the same time then even basic nursing is not possible, and often just getting

Entirely speculation, but one reason I can imagine is that if everyone is sick at the same time then even basic nursing is not possible, and often just getting fluids into someone makes a giant difference. Has there been a place/time during the pandemic where millions got infected at once in a high density, poorer country?