Stable concurrency as SBD is the best thing which increase user addoption among non-crypto people. SBD combined with rate-limited-free-transactions is a killer feature for wide global adoption.
I am not objective, because right now I am leading new startup called Prio (more details soon!) which use STEEM blockchain as backend.
One thing is sure: SBD is essential for us. Thanks to SBD, our application is super simple for average Joe, who knows nothing about technology and can use cryptocurrency without even knowing that.