Yeah but that's a bit weedy, and still speculative (he never seemed to have any intention of directing the battle- Piett was doing it).
Plus look at the new novel for TFA- Snoke in it saying the Empire fell because of sentiment, which allowed Vader to kill the Emperor. Well, the Emperor would have been JUST as distracted if Vader had not done that, and the Death Star still would have blown. Sentiment be damned- the Empire lost because its plan was crap.
You can tell Luke/Anakin killing the Emperor is MEANT to be this big, universe-changing moment, but the logic of that got lost on film because there is no clear grand-plot consequence for it.