@crangitsch: They'd probably tell you to do that because with a godet or a gore. You've got the problem of fraying, especially if you have something like satin or taffeta that shreds at the barest touch.
A couple ways around this are to serge the edge, then hem the rest. If you're using a synthetic that is 100 percent synthetic, you can take a lighter and melt the edges like with a ribbon. Practice on a scrap first, though or you'll end up with melted edges, which is not pretty. But if you melt it right, it should result in a small tight edge like on the edge of a backpack strap.