If you are doing your own songs and producing yourself, you have lots of time to go back and fix things by punching in, etc. You still may want to tune background vocals so they are a bit sweeter, but that's your call.

Unfortunately, if you are in this business trying to pay at least some of your bills with studio income, you have to make the client sound as good as is technically possible. Otherwise, they will hire a producer who WILL make them sound better.

A few years ago, I had a 15-year-old girl and her mom hire me to produce a few vocal demos for the girl. The girl was not that good. Of course her mother was paying the studio bill. After the session, the mom told the daughter to go wait in the car. The mom came up to me and flatly stated, "Your going to fix that so it sounds good, aren;t you?". Even moms know about the tools now.

To "autotune" and to "melodyne" are now verbs. They are standard production tools for many genres. You only hear them if it's been used to fix an absolutely terrible vocal, or used by an engineer who doesn't know what he's doing, or if it was used as an effect as in the definitive "Cher effect" of some years ago.

I also prefer Melodyne over Autotune.

Neither will turn a bad singer into a good singer, but they will take a pretty good singer and make them sound very good.

Virtually every track coming out of Nashville these days has been quite thoroughly tuned. This applies to most pop & R&B as well.

Like it or not, it's a part of many modern production styles.