Because the local currency would have to go trough the banking systems and if the seller's account is in any other country, then exchange restrictions are applied just the same.
They have paper money, which you can exchange for BTC. Money exchangers have been doing this for centuries with different commodities to skirt around regulations, and BTC, gold, or jade figurines are all the same at the end of the day if there's an agreed value for them.
Well, yes.. but the person giving you paper money in exchange for BTC will make their own exchange rate based on the capital risk incurred in transacting volatile goods, which is very different than transacting gold or jade figurines. Unless of course you meet a BTC collector who has no immediate plans on capitalizing on his investment.