Why can't three generations of paper money completely replace Yuan, Ming and Qing copper plates?

The social background at that time made it impossible for paper money to completely replace hard currency! Because there is little room for hard currency depreciation, paper money is like stocks. If it falls below the limit, it is a pile of waste paper! Social instability, ordinary people dare not take the risk, even big businessmen will not do so. Without the support of the mass base and the government, paper money can't replace copper money!