Steemit is powered by Graphene technology which is also what BitShares uses.
Ethereum is entirely too slow to support global demand.
Check out the unconfirmed transactions for Ethereum: https://etherscan.io/txsPending
Over 3,000 txs at the moment. This will get worse as adoption of Ethereum continues to grow, unless they can upgrade their code fast enough to catch up with demand.
There is a real market for smart contracts, and Ethereum is well placed in this domain. Maybe other projects will raise in the coming years (NEO...), but ETH was ready first !
I think Bitshares don't need to be compared with ETH. Moreover, BTS is world champion in 2 domains :
The problem is to have everyone aware about that !