Why does water electrolysis use direct current?

Every source I've found regarding water electrolysis says that it's done using direct current (rather than alternating current), but I haven't found a single source that mentions *why*.


Obviously, using AC will result in the hydrogen and oxygen being mixed together, so if the goal is to produce separate gases then DC is required. But is that the only reason, or is there some chemical process that works better with DC?


