I think you have hit is square on.
Our cases were identified immediately, quarantined, and given sophisticated medical treatment. So far, it seems that they have recovered. Thus, no spread.
It sounds like this was allowed to continue in Wuhan just long enough that the numbers began to outpace adequate medical treatment to cure/treat someone. Then you have too many people with it and not enough meds available. Then... snowballs out of control.
it doesn’t look like that scenario is going to happen here in the U.S., nor in any of the industrialized countries who are reporting a handful of cases.
if I was adjacent to China, though, I’d be updating my bug out supplies like a mofo.