Real life is rarely as simple as discrete causes and effects. The dollar being a reserve currency is the result of both advantaged position America was in at the end of WWII combined with subsequent economic policy. Economic policy alone would not have resulted in the powerhouse America became, and it certainly could have squandered its post-WWII position with bad policy.

The dollar becoming the reserve currency has given America a lot of power, however. It certainly is a factor in the way America is able to run a trade deficit and yet still benefit.

You are getting two things confused here. The original question was what privileges the US had that others do not. The USD being the reserve currency is unquestionably a privilege. That it is not the original cause of American prosperity is completely besides the point.