Yes, I agree. At most quarantines will slow the initial rate of spread. Once it catches fire, quarantines will become utterly useless. The last estimates I saw were that there WERE over 100,000 infected in Wuhan/Hubei - that was back when China REPORTED less than 3,800 CONfirmed cases. Many folks are loathe to go to hospital or self-identify as infected - or think they just have a cold. So the stats miss those folks. Today? Could be a million or more. Who nose?
The longish asymptomtic incubation period of 2019/N, the high transmissibility, and the large number of infected folks who remain subclinical (with no or minor symptoms so they don;t seek treatment) butt are virus shedders makes this strain virtually impossible to extinguish by quarantines.
Elvis has left the building.