The thing to understand here is that the ancient people who would have heard these words from a poet did not drink wine as we understand it.
Wine was a concentrated product added to water for consumption. This did a few things, but the important ones are condense calories, make the water safe to drink, and the concentrated wine product was easier to store and ship. Wine dark means this stuff.
We think of epic poetry as some kind of high literature. They were more like Marvel movies of the day. Wine dark is not a fanciful metaphor, but rather something the audience understood and fit into the meter.
Homeric verse had to fit into dactylic hexameter. Easy phrases are sprinkled throughout Epic poetry that make the scantion work out. Wine-dark sea is one of them. Swift-footed Achilles and Rosy-fingered dawn are some other notable examples.
These phrases are used when it makes no sense. The Iliad talks about Swift footed Achilles sitting down, so arguments that meter isn’t determining turns of phrase is simply wrong. It’s just an epithet that fit into the scantion.
These are really long poems that were recited, from memory to audiences. Memory was their primary storage. So there are a lot of “go-to” easy phrases that are really just vamping, but since it’s thousands of years old we want it to mean more.