Why do people think that dressing in ‘authentic’ Steampunk means your outfits have to conform to the colour range of Victorian-era photographs: black, brown, sepia, cream, and white. The Victorian era saw the invention of new dye and fabric technologies; in fact, this was one of the major marketing forces pushing the Industrialization of the Western World along at a breakneck speed. This was the era where the phenomenon of ‘fashionable’ colours came into its own.
Aniline dyes were discovered by accident when William Perkin was trying to synthesize quinine. Perkin discovered mauveine, but other chemists and scientists went on to rapidly discover other dyes like fuchsine and safranine.
Personally, I prefer the colourful cosplay over the fifty shades of brown. Not everyone agrees.