Why did Dan Larimer quit Bitshares to start Steem?

Does Steem have a feature that Bitshares lacks?
What are the differences between these two DPOS blockchains that were created by the same person and have overlapping communities?
The only difference that I know about is that Bitshares have a higher rate of inflation, but it was not always the case, and could as well reverse again in the same way that Steem lowered its inflation rate.
Anyway, I am sure that Dan's decision for is move did not include inflation rates of his own creations among its causes.