mach_kernel (not) in root Yosemite partition?

/System/Library/Kernels/kernel

 

why would they move it?

does this make it less posix compliant?
(posix newb over here)

 

In HP-UX the kernel file is in the /stand directory, e.g. the kernel file is /stand/vmunix
Linux based systems (not posix) tend to have the kernel in the /boot directory. e.g. /boot/vmlinuz (compressed kernel file).
FreeBSD (not posix) appears to do something similar, with the kernel located under /boot/kernel
I'm not so familiar with Solaris, but it could be under /kernel or /platform/{arch}/kernel depending on the system architecture. But just to make things more complicated, there appears to be a platform independent part and platform specific part.

It seems that most *nix based O/S are moving away from placing the kernel in the root directory.

 

Most of the examples you site still have a link at the root level to the kernel. At least they once did. It's been a while for me.

 

I think that in most cases that link is there for backwards compatibility with something that was phased out long ago. For example, my Debian GNU/Linux desktop has those links, but you can delete them and nothing bad happens.