PORTLAND, Ore. ( TheStreet) -- No band is an island.The last time I saw Tegan and Sara, the Canadian sisters were performing a relatively intimate set at the Berklee College of Music's Performance Center in Boston in support of their then-newly released 2007 album The Con. It was largely on the pop side of their folk-pop aesthetic, but the small room lent itself to their spare presentation and vocal-heavy songs like Call It Off. Flash forward six years and two albums later to Seattle's Bumbershoot music festival this year and the Quin sisters are on stage in Key Arena with a full backing band and big-screen background video singing their Billboard Top 40 hit Closer. There are fans with sweet haircuts pogoing in a hockey rink-sized pit, there are lights bathing the upper tiers that must have taken a lighting technician a few solid days to design and there's the faint whiff of recently legalized Washington weed in the air as mortified fans of Tegan and Sara's headliner -- Fun. -- come into the building. So how do you go from faint traces of Ani DiFranco tunes one minute to electronic dance pop produced by a fellow accustomed to working with Kelly Clarkson and Pink? Well, turning 30 and wanting to wipe away the Sarah Singer/Songwriter days of your 20s will do it, but a little cash certainly helps. As they told Buzzfeed's Jessica Hopper, the success of Closer gave Tegan and Sara the opportunity to recoup some of their expenses and make a little more for themselves by getting the song into a commercial. " I can see why some bands might find that grotesque, but it's part of the business now," Sara Quin told BuzzFeed. The fact is that it's been part of the business for a good, long while. It's only recently that it's become an essential part of it. Before a slight uptick in digital music sales and a big boost in vinyl sales yielded a 0.3% boost in overall sales last year, music sales in the U.S. had dropped every year since 1999. Yes, that date aligns with the rise of Napster, the dawn of file sharing and free music and the bottoming out of songs and albums as commodities. Where a band could once sell its music, go on tour and do fairly well for itself without being in Jay-Z/Taylor Swift territory or "selling out," the first part of that equation faded out a long time ago.