Eliminating paper fiat will have a measurably negative effect on economies. Paper money represents a more efficient form of transaction than electronic payment. For the poor who can't afford a cell phone or internet connection, paper money is their only hope of buying/selling. Getting rid of paper fiat makes transactions more difficult and also centralizes the currency aspect of economies which leads to monopolism. Centralizing power and influence in this way is strongly correlated with exploitation, predatory business practices and inequality.
Banning paper money will have a measurable negative effect on economic growth, unemployment, inflation, standard of living & other statistics. It will represent lost opportunity, a higher bar to entry for markets, greater difficulty in small businesses surviving and creating jobs. There's no upside or advantage in getting rid of paper money. And there are definitely many disadvantages.