My guess would be that nobody seriously considers Windows servers for enterprise storage. I've worked for several storage companies and Windows support in that world is something that people usually want to overlook, or to provide a bare minimum of. I.e. think about companies like Dell EMC (their storage division) or Infinidat etc... it's mostly Linux with rarely some BSD in the mix.

Non-atomic stuff is simpler on the implementation. Even if the behavior is worse for the user, it's easier to write, and you have fewer requirements to satisfy. So, not having a real pressure from the customers, it's just easier not to do this.

They mention in the docs it was somewhat complicated to use.

Very few apps need more than the ability to atomically swap a file.

And for the complicated multi write cases, a lot of software just use sqlite which deals with it.