Is ``Jessica's'' comment not far from the truth because Scala and Go have shared memory for their Actors/Processes? I know Erlang doesn't share memory between their processes which leads to concurrency; is this what she was getting at?
Her "how much pain and when" I think implies that she only accepts concurrency as practical when units of concurrency are isolated as that would reduce the number of shared data structures being updated, lock contentions and so on. There is some truth in there that I agree with.
But then again maybe she was just trolling. I for one do not like her tone her comment.