Ascorbic acid has also been suggested as a possible chemical additive to help combat oxidation. Anyway, I'm unlikely to use sulphite myself, because I have at least one good friend who's allergic to it. And I'm really hoping that better bottles and filtration will make oxidation a non-issue for me. But if you suffer from early spoilage, you might well want to look into sulphites. Yes, it's obvious, but why it's obvious may not be.
Wine is made by taking a sugary liquid and fermenting it with the help of some friendly yeasts.
Liqueurs on the other hand present a completely different environment. There is no fermentation at all, and no yeasts. Yeast is the most persnickety part of wine. It has to be coddled with the right percent of sugar in solution and the right temperature and acidity ranges, and it has to be kept well clear of oxygen. And when the wine is done, you've got to go to some great length to get rid of the yeasts so they won't make any more trouble.