That is true, but the Scottish government would be unable to print more pounds when it needed them, which would restrain its actions during the normal course of the financial year (tax revenues tend to come in at the end, but you spend throughout) and completely lock it up in the event of a financial crisis. That's likely to mean interest rates would always be slightly higher than they would be in rUK for consumers and the government, meaning higher taxes, lower standards of living and weaker public services, and no control over inflation which can be pretty important during a slump. That's no freedom - keeping the pound in this way would mean many of the important decisions about Scotland would still be made in Westminster, but that Scotland had just stopped itself being represented in Westminster. (See also the UK leaving the EU on that bit)