Ozzy had an outstanding melodic sense in crafting vocal melodies, that he couldn’t hit all the notes accurately in a live setting is another matter and nothing that a well set-up autotune could not smooth over.
Having seen Halford only a week or so ago, he is still a great singer, but no longer the Stimmwunder he was in the 80s. He already admitted using pitch correction live more than a decade ago, just a touch, if you don’t overdo it, no one will notice in a live setting. I think we’d all be surprised if other singers were as honest as him. I would not bet on IG not using a litte pitch correction live and I frankly wouldn’t mind if he did. I’ve played in bands where the lead vocalist used a little pitch correction live, it’s affordable by now and tuned in lightly it won’t sound like Cher either:
https://youtu.be/nZXRV4MezEw (To the defense of the old girl: It doesn’t sound that way because she couldn’t hit the notes in the studio, but because she liked the robot voice effect when the engineer fooled around with pitch correction to demonstrate something to her.)
Jon Bon Jovi, once a very fine singer, indeed shredded his vocal cords via overexposure. He’s frank about it in the more recent Bon Jovi documentary and also about the fact that there is no remedy for it.
The Eagles recently released a live recording from 1977,
https://youtu.be/MxQXKO194XM
all nicely cleaned up (I know the undoctored version, it has been available as a boot for ages), and every single historic vocal track plus all the backing vocals have been sent through pitch correction for the release. Don Henley doesn’t leave things to chance. Randy Meisner was a great singer, but even he didn’t hit the notes like this in a live concert in 1977.
Queen’s 1975 live recording has modern day pitch correction on Freddie’s voice and the backing vox too. It has long made inroads with “honest rock music” - but old rock fans are delusional about its alleged non-existence in the music they hear.
And I only recently learned from the remix that Robin Trower’s legendary live album had all the vocals re-recorded in the studio at the time. The remix has now reinstated the original vocals which weren’t bad at all, but they were apparently concerned about the drums bleeding into the vocal mic. These days, that bleed can be removed electronically.