The in-world items you could buy in Second Life two decades ago using Linden dollars were arguably a successful use case for micropayments.

You could buy and sell virtual items with a real-world cost far smaller than the transaction fees of a regular card transaction.

Speaking of which - that, to my mind, is the definition of a micropayment - a payment too small to be practical to administer using existing card payment infrastructure. So-called "micropayments" in games have long since ceased to qualify under that definition - they're just "transactions" now.