I also have watched Cantrill's talks. But I think you're intentionally ignoring my point, in two ways:
* You were discussing porting a Linux application, not a kernel feature like DTrace, ZFS, Zones, kqueue, etc. Obviously porting a kernel feature between two OSes that share a kernel history is going to be easier than porting to an entirely different kernel. It's almost tautological. Porting an application has more to do with whether the syscall/libc interfaces are compatible and if you take kqueue/eventports as an example you still need to do standard porting work. glibc provides BSD-like interfaces so it's not like you have to switch away from bzero or whatever -- that's not the hard part of porting code.
* You specifically stated that Linux is "off in the weeds", "doing their own poor re-implementations of tech others have already done". Ignoring how disrespectful that is, your response to me saying "the whole Unix family re-implements each others ideas all the time -- DTrace and ZFS are the exception and only three members of the family use them" isn't helping your original point.
Also this whole section is just a non-sequitur:
> And there are not different views on zones and jails. They are the same thing. [Long description of how they are different and were developed separately.] [Random aside about Linux containers and how they're a mess.] So jail and zones are similar.
I am aware of the similarities and differences between Jails and Zones, and I'm also very painfully familiar with Linux containers. Not sure why you're bringing them up in a discussion about porting applications between different Unix-like operating systems. Sounds like you just have an axe to grind.