Even Fiat like USD, has no "official" price in relation to other currencies. Various exchanges and
banks trade currencies and rates are always floating. Rates tend to converge on a single price at any given time
due to arbitrage. This is true whether its dollars or Bitcoins.
You are incorrect in your thesis. In the USA where local currency is the world reserve currency obviously no "official" rate exchange. But in other countries which live in Bretton Woods/Jamaica monetary system local currency is tightened to USD. They do have "official" rate exchange of local currency to USD issued by the Central Bank of that country. It may have different status from strict to advised, allows wide or narrow margins for commercial operations. But it does exist. So whenever business entities negotiate they do not argue, let use rate of bank "A", or bank "B", or average of rates in banks "C" and "D". They always know that can open Central Bank website and get fair "official" rate.
Just because some currencies may be pegged doesn't change the validity of my point.
Bitcoin is obviously not pegged.
Anyway, I'm not sure why you think having some official rate would change much.
Let's say such a thing existed. How does that substantially help Bitcoin adoption?