I must admit I treated autotune, and I have had an Antares rack unit for years - as a problem fixer, until the Cubase update where you could take an audio file, and cubase would graphically show you the pitch of every note, and let you change them, pretty seamlessly too.
Even Opera singers - proper trained ones occasionally slip, and comping opera is now possible and nobody need know. One of the big snags with these singers is that they cannot repeat and repeat, and dropping in type recording robs them of the feel - and they need to match the volume and tone. They get worse when you have to say "can we do one more?" Sitting with a trained singer, they can be mega critical. They spot cents and once they know they can be fixed, they want perfection. It's very strange. When I introduced the technique, I expected rebuttal - but no, their goal is perfection, so I got quite used to getting emails - in bar 22, when I sing 'celsis', the 'ce' is a tiny bit flat, can you fix it please. I think it even generates a little more money. Budgets are always tight, and my preferred way of working is to sit with them in the studio while you do a few edits. They can see how long it takes to get it right - and then when they are sitting at home with their feet up and hear a small slip, they know it will take me maybe half an hour to fix it, and re-dave everything, and they know the costs - but to them it really is worth it. When you look at the syllable in question, you find they are right. When I'm doing middle of the road stuff, some singers slide into the notes stylistically - but often, they over-cook it, and they want that fixed.
I've just put out a piece by a singer who wanted to try three or four songs, intending to pick just one, and I've discovered I actually had enough takes to complete the entire song, from what were essentially outtakes. After getting the completed vocal track edited into one, I went back and fixed every wrong note. Some were so wrong because she didn't really know the melody properly, so sung in tune, the wrong notes. I've fixed it, and she's very happy with it. A song from nothing!
Autotune in the traditional sense is probably now too blunt a tool, but the software versions can be so much more flexible.