There are many cases where Local Containers are introduced in order to replicate the design of a Server job.
For example, here’s a Server job design that makes use a single Sequential File stage that reads from multiple files, a design not possible in the Parallel canvas:
After conversion into a Parallel job the Server Sequential File is now represented by a single icon: A Local Container which hides the complexity required of the equivalent Parallel implementation. In this case the Server Sequential File is represented by two separate Parallel Sequential File stages, each reading their respective link’s files. Note that the target ODBC database does not get converted in the same was at the equivalent Parallel stage still supports multiple input links.