This would be a total nightmare. The vast majority of suppliers and customers use ‘fiat’ and they are obligated to report in ‘fiat’ so why would they internally

This would be a total nightmare. The vast majority of suppliers and customers use ‘fiat’ and they are obligated to report in ‘fiat’ so why would they internally convert it to BTC just to convert it back out? This is a recipe for misreporting and accounting fraud too.