Shouldn't GNU tar be ignoring /proc with --one-file-system?

[Kirk Strauser]

On Nov 18, 2011, at 11:27 AM, Robert Bonomi wrote:

> See the output of 'mount(8)' for the names of all the mounted filesystems on
> your machine.  

$ mount | grep proc
procfs on /proc (procfs, local)

> 
> *NOTE*WELL* that '/proc' is *not* a separate filesystem.  It is merely a
> _directory_ with a bunch of 'special' files in it.

I'm confused here. In what way isn't /proc a separate filesystem? It's even called "procfs".