Why dont you just go home… by Lush. Photo montage by Lush.
Super ephemeral street art is definitely aided by documentation, but documentation isn’t always essential to understanding the work. A performance by Improv Everywhere still means something to the live audience even if there’s no video to post afterwards, just as the lucky few who got to see Olek’s yarnbomb of Alamo could still enjoy and understand the work just as well as anyone at home seeing photos of it on their computer screen. But there are also some artists who are doing work that most street art fans and experts consider without-a-doubt to be street art, but the work is nonetheless essentially incomplete or incomprehensible without documentation. For this kind of art, a person seeing it on the street might only be seeing a part of the final artwork, or they might not be able to see the artwork/intervention at all. It’s only through looking at the documentation, typically shared online, that these kinds of artworks can be fully understood and appreciated.