grapes for wine and grapes for consumption are different, not to say they aren't edible it's just that they were bred for different functions kinda like how apples back in the day were mostly used for cider and so most apples then were barely edible and very astringent. (also with how apples reproduce it's basically dumb luck to get a good tasting apple and even then, if you get a good one you have to graft it to make more of that specific apple, which is a risk since plants with very similar if not identical dna are vulnerable to disease that can wipe it all out)
though I'm not familiar with how grapes were selectivlvely bred.