Rainbows were commonplace on everything related to kids; always on their toys, one of the first things they learn to draw to help understand the colour spectrum. They've been strongly featured in both children's films and books, as well as usually found on some charities' logos.
The hijacking of the rainbow on behalf of the progressives has probably been done subliminally to psyop kids towards it.
Friend of Dorothy referred to the writer and wit Dorothy Parker. Gay men who wanted to know who else was gay would look inside the library copies of Parker's books. Any male patron who had signed out the book was likely gay.