Well, I’m not arguing the semantics of the words “tragedy” and “redemption.” We know what I’m saying. Ben’s turn to the dark was lamentable, and I believe he should have the chance to turn back to the light.
Whereas Ben and (a handful of students with him) killed only the remaining students (less than a dozen) after his teacher tried to murder him.
Unless we are believing Luke is lying, Ben had already turned to Snoke by the time they had their fateful moment in the hut.
I don’t see any reason to doubt Luke, but we’re talking about Ben burning the temple and killing the other students, which happened after Luke entered his hut. Whether it would have happened anyway or if Luke pushed him over the edge is somewhat ambiguous at this point. But I think you could very easily make the argument that Anakin would’ve turned to the dark side without the extra motivation of seeing Mace swing a lightsaber at Palpatine.