Social distancing, contact tracing and isolation of the sick work well, and that was almost certainly the critical portion of the response.
For example, this paper makes a solid argument that the travel ban delayed the epidemic across china by only a few days:
https://science.sciencemag.org/content/early/2020/03/05/scie...
- Lockdown in northern Italy: People ran to the south taking the virus with them. - Schools closing, folks asked to work from home in Madrid: Families drive to the coast where bars and restaurants are full.
I agree that in a place where compliance with social distance measures is high (I'm thinking South Korea, Japan), that would be enough. But that doesn't work everywhere.