Sending money without government interference to relatives living in countries with strict foreign exchange controls (Argentina, Lebanon, Turkey...) is one quite legit use case.
Most arguments for cryptocurrency are just as weak as this one.
Crypto allows my family members to bypass arbitrary restrictions set by one such kleptocrat right now so the benefit is very much more than marginal.
By sending your family money, as crypto or US dollars, you have to assume some percentage of that money is going to end up in the kleptocrat's pocket. If the funds are eventually settled through official exchanges in the country, its very likely that the government gets a cut of the exchange transactions. If its being settled by unofficial exchanges like street exchange vendors, those individuals probably pay some bribe or tax to operate that eventually makes its way back to the kleptocrat. Additionally you are offering the kleptocrat increased liquidity by operating with crypto. Assume the kleptocrat is the largest buyer of cryptocurrencies in their country.
All three of those countries have restrictions/regulations on converting crypto currencies into local currencies - doesn't crypto just move the the problem to converting it to local currency?
1. You want to convert the "hard" currency into the local currency
2. You want to convert the local currency back to the hard currency
3. You want to send hard currency back
Often there are official rates set by the central bank in these countries, and then there are black market rates. Banks etc will convert hard currency to local currency only using the official rates, which tends to be a lot lower than the black market rate, so you get shafted by that in the first instance. Then, when you want to convert the local currency back, banks won't sell it to you because the government does not let them sell hard currency to the general population. Finally, sending hard currency abroad is usually de facto (and sometimes also de jure) banned so your money can't leave the country once it's in. And as a last resort if you say screw you I will withdraw e.g. USD notes and take a flight, banks will refuse to give cash hard currency.
Obviously crypto lets you sidestep all that as nothing can prevent you from sending USDT from your wallet.
While it is useful for this case, it is not 'legit', in that its purpose is to by-pass (break even) laws of the country with the capital controls. In that sense, money laundering is also a legit use-case.