Contact Approach -- WX reporting

Jim Macklin wrote:

At airports without official weather reporting,
the pilot can report to ATC that visibility is such and such
and he can maintain VMC and request a contact approach, the
pilot become the weather observer.

Can you really do that? A pilot's guess of ground visibility from
aloft is good enough for the FAA?

The advantage is that
the IFR clearance is still in the system and the pilot has
the "out." It keeps an active flight plan, which is nice er
than canceling IFR and then nobody will look for you.

I wouldn't consider search-and-rescue an "out." The only thing I can
think of is that staying IFR keeps other IFR traffic out of your hair.
Is there another advantage?