I'm going to revive this thread with an argument for an artist who
actually influenced stuff politically: R.E.M.
For the longbox release of their 1991 album
Out of Time, R.E.M. added a form postcard that you could send in to encourage senators to pass the Motor Voter Bill from back in the day. Since the album sold four million copies, plenty of them in longboxes, Rock the Vote ended up delivering over 100,000 postcards to the United States Senate, something which unarguably helped the bill pass later.