While modern people make that connection, that is culturally dependent. The color terms available to speakers of a language, and what objects those terms can be associated with, change over time. In the case of the Greek word for "purple", it was connected to a dye and therefore used for clothing, but one shouldn't expect it to be used for wine.
"Wine-dark sea is a traditional English translation of oînops póntos (οἶνοψ πόντος, IPA: /ôi̯.nops pón.tos/), from oînos (οἶνος, "wine") + óps (ὄψ, "eye; face"), a Homeric epithet. A literal translation is "wine-face sea" (wine-faced, wine-eyed). It is attested five times in the Iliad and twelve times in the Odyssey[1] often to describe rough, stormy seas. The only other use of oînops in the works of Homer is for oxen, for which is it used once in the Iliad and once in the Odyssey, where it describes a reddish colour. The phrase has become a common example when talking about the use of colour in ancient Greek texts."
Says anyone familiar with Ancient Greek, and also anyone who has followed linguistics (even in pop-sci form like Deutscher’s Through the Language Glass) recently. The comment by fsckboy, which was already there when you commented, gets it. For the Greeks, the connotation of wine was different than purple, purple was not a basic color term in that stage of the language, and πορφυρός was used only in the context of purple clothing and the dye used to make it.
