The vintage is part of the product. The same wine from two different years has a different cost, a different price and a different life, and a system that treats them as one line loses track of both.
Reordering is often impossible. A grower makes a few hundred cases and that is the end of it, so the question the numbers have to answer is not how fast something sold but whether anything like it can be found again before the shelf goes empty.
Tastings need running as events. Places sold, cost of the bottles opened, what was poured and what sold afterwards is what tells you whether the evening was marketing or just a nice time.
One customer is really two. The Tuesday bottle and the anniversary bottle come from the same person at completely different prices, and a shop that recognises which purchase is happening recommends better and sells more.