Government would still have to set up a center of "approving" unknown money coming from other sources into local economy. These centers, as you can expect, will be massively bribed by everyone who needs to launder their tainted coins.
Also, governments will be much more limited in power when they can't print their money at will and do any "deficit spending".
Also, governments will be much more limited in power when they can't print their money at will and do any "deficit spending".