As soon as the light hits the sensor, everything from there is effectively "post processing".
The only difference is the tools used to post process and the level of hands-on control you have.
I must confess that I am completely against imposing any such - in my view - arbitrary rules for the creation of images.
Having "partial" rules simply opens up the forums for drag-out discussions about "too much" vs. "acceptable". Using a sepia-filter is fine when on the lens, but not if applied in Photoshop? Using sepia tones is OK, but using crazy neon is not? Selectively blurring in Photoshop is no ok, but smearing vaseline on your UV filter is?
We live in a digital era. All the most bought, most profitable, most seen and most revered images are all post processed.
I personally think we should stay away from this entirely line of thinking - if patti use a Daguerro-type filter to turn her color image into a startling 30's Noire B/W image it doesn't take anything away from me - in fact, I get to see something I otherwise wouldn't - the pure and unfettered expression of patti's creative mind.
My 1.203.641 cents..lol