Rapid startup: lambda is a tiny subset, and not really server application. A server app could take minutes and would still be okay, because they are designed to run for a long time. Even in case of scaling minutes are more than okay since deploying a new instance takes a similar amount of time.
excellent sandboxing: you usually only run your own code connected to db and other very privileged services. If there is a vulnerability it is a very big problem with or without sandbox
no blocking code: i’m not up to date, but node doesn’t have a strong parallelism story at all, compared to the JVM, Go, .NET