It allows you to opt out of the monetary system that's been imposed on you by your govt. This might be less of a big deal if you live in a developed country but it's a big deal if you live in an unstable country.
Say hypothetically you lived in a place like Cuba where the government had banned things like renting out a room to foreigners or selling them a coffee as was the situation when I was there. Taking payment in the local currency would be kind of useless as you couldn't buy much with it and taking dollars, euros or whatever was illegal and could get you in prison if they caught you. However if your customer transferred some ether to a wallet you controlled with a private key but without your name on it it would be quite hard to catch or prove.
Why would it be quite hard to catch or prove? How many fiber optic lines do you think go to Cuba? They could lock down the internet the same way China does. Maybe they haven't gotten around to it yet, but that's not a long term structural argument for the utility of cryptocoins its a temporary moment-in-time argument. Kind of like how at one point a big advantage of buying things on the web was that you didn't have to pay sales tax -- that's not anything inherent in the web, it was just an artifact of governments' lag.
Say your customers are us tourists and they send from a coinbase account to some ether address. Dunno how they'd track that.
I don't think it's a lag thing - decentralized cryptocurrencies are just hard for governments to stop. Similar how governments would like to stop people paying cash in hand and avoiding tax but have never really been able.
You don't need to hold physical cash to hold USD. You could have a bank account in London, Geneva, Paris, or New York with your pounds, franks, euros, or dollars. If you need to leave the country, your savings are already outside of it. Just like your bitcoins.
The answer seems to be that repressive countries haven't yet put in place effective mechanisms to be repressive with respect to bitcoins. But there's zero reason intrinsic to bitcoin to expect that to continue. On the contrary, since everything is digital the choke points are easier to control, not harder.
You can't opt out of the monetary system that's been imposed on you by your govt, because your govt's desires are backed by the use of force[0]. Short of moving to a different country, paying off the enforcers, or going into open rebellion, everything else is a fantasy.
That’s not an option for most people and it has huge risks. Try buying anything big with no disclosed income sources or living well beyond your means and you’ll be getting caught by the people looking for drugs dealers, smugglers, etc. Most countries are pretty good at that.