The sad thing is, the potential for Sylvansas' character to have a "redemption" arc was their....
...over a decade ago during WotLK.
Sylvanas wasn't really in need of a 'redemption' arc back then. She was just some edge-lord 'tortured/shades of grey' character who was doing her best while seething over Arthas and what he'd done to her.
The subsequent shit like with burning Teldrassil, etc. necessitated a 'redemption' arc in order to rehabilitate her character, particularly since they built such a wobbly foundation that required Sylvanas to be a focal point. This goes into how Vol'jin was slotted in lightning-quick fashion and how Sylvanas' importance was played up by the loa or spirits or whatever.
The problem is that Danuser (beyond being a shit writer and storyteller) is very ham-fistedly trying to force Sylvanas down everyone's throats so she 'needs' a redemption arc.
There's potential for a story where Sylvanas continues to be an ice-cold bitch and is just a ruthless character who does things her way or whatever. There's also potential for a story arc where she does get redeemed or turned into a more virtuous character which, while really fucking overdone, is still a tried and true story that people enjoy.
What we got was some fan fiction level nonsense that came at the expense of other established characters. It's no different than some idiot introducing their OC character and having them come off as awesome and kewl while cutting off the legs of existing characters.
The boner Danuser has for Sylvanas is ridiculous. Afriasiabi did nothing wrong.
E: And piling all this crap with Sylvanas on Furor doesn't make any sense when the wheels were in motion with her since at least like 2014 or so, which is when Legion would've started development (announced August 2015 and released in 2016.) It also doesn't make any sense if you have any idea how creative environments like that work. The narrative that Alex came in and kicked over Danuser's pretty narrative sandcastle doesn't hold any water.