You don't think larage multi-node systems should be viewed as examples of Alan Kay's ideas? Then you have no clue what his ideas are. Alan Kay explicitly said that the only think really reflecting his idea of object-oriented systems is the internet itself.

What you claim isn't part of his idea is the very DEFINITION of his idea.

In the Alan Kay sense, operating-system are far more object-oriented than Java. In fact Java isn't object-oriented at all.

You keep thinking that "true" OOP is whatever Java does. It isn't. You cannot talk about these system not needing "true" object-oriented systems when that is what these systems are. Java isn't.

Looking inside the Linux kernel? As I have tried to explain, object-oriented systems exist at different levels of granularity. At an OS level we would think of the processes and how they communicate as the OO system. How each object is implemented is irrelevant from that perspective.

No systems got split up despite using the same technology. The original Unix was split into a multitude of separate programs all written in C. It was more flexibile with small programs communicating with each other than a building a large monolithic system with one large C code base.

The ideas of Alan Kay is to think recursively at all levels about this. The internet is made up of messaging objects, where those objects are computers. The computers are made up of messaging objects which are processes. His idea was to continue into those processes and split those up into smaller parts also sending messages to each other. Or rather that is one way of doing it.

That point was to reuse the message passing paradigm that works so well at a large scale, and re-apply it at many different levels.