No, plumbing is taking prebuilt pieces like pipes and elbows, joints, valves and just putting them together.

There are plenty of software that is not about taking pre-existing packages and gluing them together, but rather involves construction from the ground up. Building a CRUD app using an existing framework, and an existing rest API with little to no custom business logic is plumbing.

Using sci-kit for your ML app is plumbing. Writing your own novel ML/deep learning algorithm, shoving the data in and out of GPUs is not plumbing.

> Writing your own novel ML/deep learning algorithm, shoving the data in and out of GPUs is not plumbing.

This is plumbing as well by your definition. Writing your own novel ML/deep learning algorithm also take "pre-existing packages" and glues them together. Unless you are actually going to write your own custom OS, Language and drivers you are going to reuse stuff.

I don't think there is anything wrong with using pre-existing packages and the like. We all are doing that anyways unless your are Terry A. Davis off course.

Your distinction doesn't hold up to analysis: at some level any system can be said to consist of elbow joints - eg. "processor opcodes are just elbow joints." The same can be said not only of the subsystems but also the intellectual heritage of so-called "original" systems. Nothing and everything is new. News at nine. Someone watches the news. They create a new system ever so subtly influenced by yours. Ad infinitum.