Heh. I wholeheartedly agree that S/P/R would reject a large number of current singers, but I tend to side with Boner -- it would be more the Brittneys & Jessicas than James Blunt.Mr. Blunt falls into the "Singer/Songwriter" category that appeared in the 60's. They are given considerable leeway with regard to vocal technique. (OK by me, I love that stuff.)
There used to be singers; and songwriters -- and rarely anyone who was both (except among folkies). Many songwriters were huge stars without ever humming a note (Berlin, the Gershwins, Porter, Mercer). Tin Pan Alley and later the Brill Building were like factories for hit songs.
In the 60's, Carole King, Neil Sedaka, Neil Diamond (all Brill Bldg peeps) and others started to record their own stuff...lo and behold. Other "early" singer/songwriters are people like James Taylor, Joni Mitchell (swoon), Cat Stevens, Carly Simon, John Denver -- Bob Dylan (though you could say he's a folkie too). People talked about Laurel Canyon instead of the Brill Building. A genre was born.
In this day & age, some consider artists writing their own material the norm -- some even openly deride singers that don't write. I think that's a shame. Singing and songwriting are two separate talents. If you can do both well, incredible. If you only do one well, you're still incredible.
Man -- did I ever wander off topic. Sorry -- anywho, James Blunt, Damien Rice, KT Tunstall -- "new" singer/songwriters that have earned their careers much more than Brittney...yet won't be singing any arias soon.