When traveling theatre companies would happen upon a town during the 16th century, they would present a letter of recommendation. This would let the town know that the present company was not a cavalcade of delinquents but performers of merit who had a sponsor that could defend them if the need arise.
During the latter part of the 20th century, a theatre company known as The Living Theatre had little to no legal sanction for their activities. Wherever they would go from city to city, country to country, looking to stir up social change with their methods and productions. Sometimes the push back would lead to arrests and even deportation.
There are musical movements that sparked change which did not proceed like some companies of 16th century. Ornette Coleman did not have letters of recommendation to ensure that he had the credentials to play in the way that he did. There was no sponsor that punks could rely on just in case things went wrong. Change was acted upon in an unbridled way. Like The Living Theatre, change came about on one’s own terms and often in contrast to the present terms.
Letters of recommendation exist in music under various guises. The question becomes whether these imply a positive impact or smother it instead.