Many EU countries have limits on cash payments, and the EU will enforce a union-wide limit of 10,000€ in 2027. Of course, this limit won't be reevaluated over time, so the real value will decrease with inflation.
The use case would be for transactions between individuals. A friend working at a large industrial firm told me recently that crypto would solve a problem that they have in Asia: orders are often done during auctions from the producer, and require instant payments; however the payment rails take two weeks to clear a transaction. Crypto would fix this.
The fact that it's not widespread doesn't mean that there isn't a usecase.