i dont disagree on the choices he made regarding durotar. but i do believe that people extrapolate that into the crazy Garrosh did and the normal Sylvanas is doing. Garrosh didnt lose because he attacked people left right and center, he lost it when he became racist to anything in the horde that didnt walk hunch backed and would rather use wood to make spikes on buildings than an actual roof for the hut. Thrall had nothing to do with that.
The horde being honorable doesnt make it into alliance 2.0. The choice to kill so many in Ashevale (the place was flooded with wisps due to dead night elves) and then going to burn teldrassil had nothing to do with what Thrall did. If wood and resources were the issue then Ashenvale would have been it. She chose to burn it cuz some new night elf said some words to her.
every character makes mistakes, otherwise it would be pretty damn boring or worse, become Anduin. Where your mistakes turn into gold too. Thrall made some mistakes definitely, but what Garrosh and Sylvanas did is all them. That whole line of "you made me what iam" before his ass got zapped was right in character from the dude who got upset the moment you made fun of his daddy.