That's how people make money, you can't restrict people's legitimate money-making schemes, no matter how "unfair" it may seem to newer players.
Plus, if there were two separate markets, the value of items, from Chronos to Void, will drop like a sack of rocks, because there would be twice as much of each item. Then, the devs would have to restock twice as many items, which doubles the depreciation of items even further, an exponential decay model which will make items virtually worthless.