We (bitcoin enthusiast) often preach that investing in Bitcoin is a hedge against inflation. If inflation is the main problem in these countries, how do you think Bitcoin could help solve their economic crisis?
Here is what I think, since things are not working in those countries then there is no need of them always investing in the economy because it is not going to grow and help them out of the inflation that they are already in but if they were to buy Bitcoin and keep on holding for some years, they will be capable to get a good return then when they put the money into their economy. Bitcoin has always been increasing in price for many years while the economy of the countries you mentioned has always been falling. When the countries also adopt Bitcoin as their official currency, it will make them to have an advantage since the economy of their country would not affect the price of Bitcoin and Bitcoin will always be seen as a stronger currency when negotiating for deals on important into the country.
As a Bitcoin enthusiast myself I shouldn't, but I'm going to play devil's advocate. You are right that in these countries it's almost impossible to compete even with their best efforts, but relying in Bitcoin may end up being a failed experiment, and few rulers want to assume that political cost this risk implies.
Bitcoin is highly volatile, and a change of legislature during an accumulation phase, which is the most probable escenario, could be disastrous for the Government in charge. In addition, the fact you mentioned that "Bitcoin has always been increasing in price for many years while the economy of the countries you mentioned has always been falling" doesn't mean that it will necessarily continue to be that way.
Speculating is easy, but difficult decisions in the real world are not.