Well, he obviously wanted to make EOS, so there's that.
Also, there was internecine conflict.
There is also the dismal reality of oligarchical concentration of Steem into the wallets of the accounts with the most stake. Steemit has the worst GINI of any nation on Earth, and the distribution is more skewed by the day.
While the white paper envisioned ~30% of rewards being distributed to the 'masses', less than 1% of stake is held by 99% of accounts, and, as I said, it's getting worse by the day.
@dan stated that it was broken, but lotsa folks profiting from the present arrangement don't want it fixed.
I guess these are good reasons. He didn't tell me though. I'm guessing.