Why is FLAC Streaming over HTTP done with Ogg encapsulation instead of natively?

All of the current FLAC streaming implementations (such as Edcast with Icecast) seem to use Ogg as a container for FLAC while streaming.

1. What is the reason for this?
2. What are the drawbacks of not using Ogg, and streaming the "native" FLAC stream instead?

I've done some tests streaming FLAC over HTTP, and it seems to work just fine in VLC. FLAC seems to be built in such a way that frames can stand independently, making it robust against stream corruption and/or dropped frames. Given this, I don't quite understand why wrapping FLAC in Ogg is necessary.