Why are rainbows a symbol LGBTQ pride?

An article on Bustle about how the rainbow flag became the symbol of LGBTQ pride interviews Jonathan Katz, about the role of Gilbert Baker in creation of the flag in 1978. There is some debate as to whether Gilbert really was the first person to come up with the idea of a rainbow flag to express queerness, he said, adding that “Gilbert is the one who has been credited with it. He claimed it. He was insistent that it was his.”