Fair point, but then classical music is dead too. 12 notes (and not all possible combinations of them are pleasant to the human ear), an orchestra set up, you might have more options than with a four- or five-piece rock band, but you hit the wall eventually.
"Truly original" is of course a high standard. I guess The Beatles, Hendrix and Frank Zappa pass that test, but even in the seventies there was very little "truly original", much was just refinement of previous ideas. Don't laugh, but I thought The Police sounded like something else when they arrived on the market in the late seventies, that mix of reggae, Summer's weird chording, Sting's sparse, but dominant bass playing, the overzealous drumming, the falsetto vocals, it sounded quite new. But I also remember how they were derided as "white man's reggae played by prog has-beens" in some quarters.
And for the avoidance of doubt: I never bestowed "true originality" on Deep Purple, they forged their own sound by doggedly hanging on to that Strat/Hammond twin riff attack, whether it was en vogue or not, plus were unafraid of long improvisations and unafraid to swing rather than plod, but the ingredients of their music were always plain to find with their predecessors or even contemporaries.
