Yale Researchers Prove That ACID Is Scalable
For instance, Neo4J is a scalable graph-based "nosql" DB with ACID.
Is Linus Torvalds Speaking for Linux Anymore?
Windows is a platform that sits on the NT kernel. Debian is a platform that sits on the Linux kernel. Platform is a word you can bend all you want, but operating system has a tried and true definition.
The not-so-arbitrary line is quite clear: If it runs in kernel space, it's low level. If it runs in user space, it's high level. If you don't know what these terms mean, do some reading.
There is blurriness in systems like Minix 3, where the kernel dispatches quite a bit of work to user space services. But even then, the dependencies (code paths) make it clear what is the OS and what is not. There is no such blurriness in MSWord or fsck. The NT kernel has no dependencies MSWord. Similarly, the Linux kernel doesn't need any of the code in fsck to perform its work.