How come singers sing out of tune?
I recently watched a couple of youtube videos where these guys go through famous records and their vocal performances and show how autotune makes them sound weird. In both videos, the singers don't really hit the notes right on tune, including really good singers like Aretha and Freddie. There are points where Aretha hits tones between actual notes and points where freddie is off-pitch, or holds a pitch that eventually goes sharp/flat.
Now, I obviously wouldn't call any of these singers bad and I love all of them and their performances. I also can't really notice any of these imperfections unless I'm listening to the isolated track and really focusing. All these performances sound good to me.
But, when I've looked up how out-of-tune you can be as a singer, I've seen suggestions of 5-10 cents, meanwhile these performances have some pitches hit that are ~50 cents off. I realize that hitting notes as close the to the perfect pitch is more important on prolonged notes than short ones, but there are examples in Freddie's performance that even don't meet that. The example of Buble autotuned to snap to the grid doesn't sound great to me, even the parts that aren't super robotic.
It leads to believe that what makes a good vocal performance is primarily the quality/timbre of the voice and how well the performance fits the song, off-pitch notes and all. I.e. if it sounds good, it is good, whether its snapping to the grid or not. The subtleties in how off-pitch a performance is, lend to its character and emotion. And that maybe a person's voice has a lot more leeway for "error" than a piano or guitar, similar to how film photography has more leeway than digital.
Videos I referenced: