Ivoreyy

Most textile dyes in this time period did not hold their color as well as modern day clothes. And they would fade rather quickly, usually after even a single wash. While bright, vibrant dyes existed, if you saw them regularly on someone, that generally meant that they were constantly buying new clothes. 

The concept that purple (or really) vibrant red was the color of nobility was rarely due to sumptuary laws, but just that those were the hardest dyes to keep vibrant after a wash, so they were only seen on brand new clothing and only the Supreme rich could afford that for every day life.