The story that I have always heard (and have also heard others dismiss as apocryphal) is that in the 1930s the body overseeing British cycle racing banned the use of any identifying branding on bicycles and riders, so companies that wanted to be able to promote their bikes (or frames) in racing needed to find a visual "hook" to show spectators whose bikes were being ridden and won on, and thereby sell more product. So making peculiar frames (Cf. Hetchin's "vibrant stays", Baines' "flying gate", Bates' "diadrant" forks, Granby's "taper-tube", Thanet's "Silverlight", Sun's "Manx TT", Paris' "Galibier", Saxon's "Twin-tube", Moorson's "Duralite", etc.) was the workaround they found.