@Ju Lee In general we really like Docker because encapsulates the environment needed to run an application really well. This is very user friendly as it means a user only needs to setup docker not specific dependencies like the implementation languages and tooling etc..
This is especially helpful when running connectors because each connector has different requirements. Some may be implemented in e.g python or ruby or go, and even within the same language there are differences in dependencies or the required language version. Managing all this without using an encapsulation layer like docker becomes pretty tricky