It's a token of recognition that other parties do need your goods and services and hence are backing a currency of your issuing as a legal tender. The more part

It's a token of recognition that other parties do need your goods and services and hence are backing a currency of your issuing as a legal tender. The more parties are involved in the trade with the same currency the more transactional trust the currency gets (as non-issuing parties could credit one another in the same currency for future purchases of various kinds from the issuing party). You can ask yourself a similar question to get an intuition about the importance of the move: what's the difference between IRS accepting payments in Bitcoins or dollars vs. accepting only dollars?