Technically speaking, isn't that how most all hand tool warranties work? Normal wear and abuse isn't supposed to be covered. Now, we've all gotten spoiled by the Craftsman "satisfaction guaranteed" idea - take any 'ol POS in for any 'ol reason, and get a brand spankin' shiny new one to replace it for FREEEEEE!! Except I believe even Sears could (and at times has, if I remember some other posts here and elsewhere) refuse warranty for the same normal wear or abuse issues - it's just that they infrequently, or inconsistently, do that.
That said, still sounds to me like wrenchr is gettin' the shaft from Stanley/Proto - broke is definitely different from worn out and should be covered. Hopefully I'll never have any problems with the Proto/Blackhawk ratcheting box wrench set I recently got off flea bay (for $22). They look awful nice and shiny - would hate to toss them in the trash...