Summarizing & paraphrasing :-) Greece instated capital controls virtually over night, likely illegally as there is freedom of capital movement in the EU [1]. The money on a bank account resides in a particular country, so its legislation applies. Which country's legislation applies to funds in a globally distributed blockchain, whose copies reside all over the globe?
[1] https://www.bbc.com/news/business-33303540
edited for spelling
If you were Lebanese I would argue that having a bank account was a silly thing to do. Foreign bank accounts were illegal/difficult and domestic bank accounts are now worthless. You could own crypto or some kind of real good, such as a warehouse full of a commodity like wheat or diesel. Those are your options for hanging on to your wealth.
Bitcoin fixes that and removes the middlemen.
The point about currency collapse is interesting to me, because (like almost all crypto apologist points) it assumes you already have a bunch of it/made a bunch of money on it before the bad thing happens. Everyone else gets to suck eggs, as the saying goes.
Of course if everyone in the hypothetical country had crypto, it would cause the crypto to collapse as well…