It's not. It's way easier and cheaper to send a bank transfer or wire. Bank transfers and wires also offer more privacy.
Unless you're actually going to directly use the cryptocurrency (which is generally impossible), it needs to be converted to/from fiat, which requires a bank transfer.
For you maybe, but not for me. Wire is 15 usd on receiving end fixed + some percentage of the amount sent. An ethereum transfer is 2 usd or so into my exchange and exchange charges nothing for withdrawal. Wire transfer takes 3-4 days in best case and bank calls me for some bs after 10 days in the worst case and I have to talk to them to approve it.
So after 20 mins of clicking some buttons I get my fiat currency in my bank account. And it costs 2 usd + some negligible amount.
Unless you're actually going to directly use the cryptocurrency (which is generally impossible), it needs to be converted to/from fiat, which requires a bank transfer.