Etherum is about Bitcoin trading, right? And this site incorporates, or could incorporate Etherum as a topic. So why is there a separate site for it, instead of making those questions part of this site?
Ethereum doesn't have anything to do with Bitcoin or "Bitcoin trading" other than the fact that the only way to buy Ether is with Bitcoin.
Ethereum is a completely new and independent system, not even a fork of Bitcoin. It has its own specific community. It only makes sense to keep that separate. Bitcoin.SE can already be confusing because of the supported bitcoin forks.