Ditto for photography. To take an image and retouch it, or to artificially saturate colors can make a great picture. But with a raw photo it's even more interesting to think that scene actually existed and someone captured it for us to look at.
In either case, I can enjoy the work but will only be impressed if I know that it's authentic. This is more true than ever today.
Holography, you can't currently fake that.
In music are you allowed to use amplifiers and speakers? They can add a lot of color and distortion. How about reverb? Rooms that aren't there. EQ to remove unwanted frequencies? Synthesizers? Digital effects? At what point is it not authentic anymore?
Same for photography. Are you allowed to touch the aperture? ISO? Shutter speed? Flash? Digital camera? At what point is it not authentic?
If you mess with the colors of a scene, you're not taking away artistic control from that scene.
You also don't put limitations on the post processing art; you're not doing it to fool anyone.
There is post processing in music that is obvious art in an analogous way, like taking sampled sounds and re-mixing them to create new stuff. There are effects that are obviously effects. I'm not going to scoff at a great studio reverb, or some echo applied to a vocal or whatever. Nobody is saying that this was recorded in some fjord in Sweden with real echo bouncing off a distant ice wall; there is no lie.
The thing is, I somehow don't hear the studio's creative input either when I hear the latest auto-tuned Fido or Bowser. They're just applying some automatic something that's supposed to make the dog sound like a more able dog.
This is like when people just batch apply the same color enhancement and sharpening of their Florida vacation pictures. I've seen one instance, I've seen them all.
Take the fantastic singer with great technical skill. Most pitch correction algorithms, as far as I know, are strictly based on equal temperament / 12TET. Fantastic singers are capable of hitting the right harmonics, some of which are not 12TET. Fantastic singers slide into notes, they use vibrato, they add "blue notes" (https://en.wikipedia.org/wiki/Blue_note). If you over-apply pitch correction, in other words, you could easily make a fantastic singer sound worse.
Let's also take the singer who is technically a bit pitch deficient, but has "character" that makes up for it. You don't want to make this type of singer too in-tune, either. Too much tuning might remove the "character".
I understand in the industry there are some engineers that are good enough to selectively apply auto-tune, to only fix obvious issues, and avoid the pitfalls. There are also some productions that just apply auto-tune to everything with no consideration of the content. The later will probably work for glossy pop productions, but if I was a really good singer (or a singer with "character") I probably wouldn't like the results.
The problem is, I'm not sure though that even a pure alternate tuning can work though for all examples. EG: for blue notes, what is "correct" varies with performers and style.
Now, I'm more talking about the "automatic modes"; I understand Melodyne offers a pretty impressive level of editing control (Antares did too from what I remember). So it would certainly be possible to get a really great take, and then hand-correct any truly off notes to whatever frequency you wanted.
As in many things (see: Photoshop and model photos), a lot of the reaction to the tool is less on how it could be used, and more on how it is being used in glossy "crap singer pop idol" productions.
Only it's about neither, but more about hot bodies and rich marketing campaigns.