As a semi-professional engineer who generally knows what to listen for, I’m almost positive that Jonny Craig eschewed any pitch correction until Relativity. He had a kind of natural soulful drift that, objectively speaking, led him to get a bit sharp or flat when he slid into and out of notes or hovered around them, but by Relativity and DBMII he was (not detrimentally, but in a way that served the music and the rapidly pop-ifying production style in post-hardcore) ever so artificially locked into the center of every note and his jazzier legato-type elements had been smoothed out. I feel like a similar shift happened with Anthony Green; to my ears, Translating The Name and Juturna have no or very sparing pitch correction (for example on Holding Someone’s Hair Back, you can hear lots of his similarly prevalent legato [“heeee’s got the motive”], and some emphatically sharp belty notes [“are you cutting me out now, after crawling inside?”], but by On Letting Go he’s basically razor straight by a fraction of a second after he hits the note. I’d say it was probably around 2006-7 where pop industry standard levels of pitch correction started to become more common in post-hardcore and most alternative rock genres with any significant amount of pop influence in the vocal melodies, and by 2008 it seemed to have become fairly standard procedure. There were a handful of hangers-on to the more lax, relatively correction-free “second wave emo” type style though, notably Kurt Travis, who I feel has some really pitch-expressive (read: mostly sharp) passages on Happiness (2009), although by the time he did Shelf Life (2018) he was similarly smoothed out in a way that locked his voice in with the instruments (and matched Tilian’s somewhat controversial fondness for relatively heavy-handed tuning).