> PowerShell's object pipeline is functionally analogous to function chaining in languages like Ruby, Python, and JavaScript

No, in those languages function results are bound upon returning from the function. PowerShell's pipeline would be more like function chaining where each function is a co-routine that can yield partial results, which would make it considerable more complicated.

So your attempt at trivializing PowerShell fails from the start.

For your information, here is roughly how a PowerShell pipeline is set up, processed and torn down:

1. BeginProcess is invoked for each command in the pipeline, starting with the last command of the pipeline, working towards the first. When each command is initialized this way, it can start receiving objects from preceding command on the pipeline. Each command may start produce objects already during this phase, as all subsequent commands are ready to process them. If it produces objects, ProcessRecord of the subsequent command is invoked immediately.
2. ProcessRecord is invoked on the first command of the pipeline. If it yields objects, ProcessRecord of the subsequent command is invoked for each object, thus "pushing" objects through
3. EndProcess is invoked for the first command of the pipeline. It it yields objects, ProcessRecord of the subsequent command is invoked for each object. When EndProcess completes for the first command of the pipeline, EndProcess is invoked for the subsequent command and so forth until EndProcess has been invoked for all commands of the pipeline.

As you can see, each cmdlet has 3 phases: initialization, processing and completion. All cmdlets (functions?) become active at the same time, with the control flow passing to each command (function?) multiple times during each phase. This can be implemented in any turing complete language, but function chaining is a lame attempt at trivializing it. Throw in reactive sequences and it may get closer.

Consider how Sort-Object (alias sort) is implemented: It does nothing during BeginProcess, during ProcessRecord it adds to an internal collection but does not yield any objects (yet), during EndProcess it sorts and yields all of the collected records. This is clearly analogous to how sort in byte/text stream is implemented: When the process starts it does nothing but initialize and starts listening on stdin, for each "line" on stdin it adds to an internal collection, and when stdin is closed it sorts the collection and writes the "lines" to stdout. 3 phases.

Even so, it doesn't really matter how it is implemented, a shell is inherently about how you interact with the shell.

> PowerShell's object pipeline does not exist outside of the .NET runtime and you can not stream objects between arbitrary executables outside of the .NET runtime.

You are locked in the Unix view of the world and is unable to consider that long standing assumptions about "the way to do it" may need a refresh. If you want to leverage objects for system management then yes, you need a system-wide object model. Unix was not built with an object model. Windows was sort-of build with an object model (handles) but it is not versatile enough as a system-wide management model.

However, the good thing about objects is that they are abstractions which can easily wrap existing operating system concepts, such as files, processes, access control lists, drivers, users, groups, network connections etc. .NET is a mature object model and with a lot of tooling. Building PowerShell so that the abstractions over network adapters, users etc become represented by .NET classes enable a lot of tooling and infrastructure right from the beginning.