What's the taper for?

[tool-nut]

I think this has been brought up before, but I can't find any threads for it. What is this tapered wrench for?
http://www.ebay.com/itm/Snap-on-3-4...428W-Tapered-Ends-/330774105293#ht_3057wt_754

Is it only an obstruction wrench or is there a more specific function?

 

[RedVise]

I have a Herbrand 173 Valve Stem Wrench, marked For Valve Stem Nuts Only.
AA has a pic but you cant really see the taper.
Funny, google search does not return any data for the usage of this wrench. Really ? for a snap-on wrench, no data ?

Brian L.

 

[Dale B]

I have a long pattern 5/8 cornwell with a tapered box end. It's stamped "no warranty"
I had a snap on that was tapered like the example , but I cant find it ...I remember the p/n didn't show up anywhere.