One could argue Palpatine being focused on turning Luke distracted him from supervising the battle outside more closely.
In all the films to date, we’ve only seen three Jedi go bad. And only one of those was a master. Even if the Jedi ways were abandoned, that isn’t going to stop the Sith from popping up.
I see what you’re saying. I also see what RoTJ’s narrative intentions are, I just think it gets lost in its own logic (or lack thereof). In the SW universe circa RoTJ, the Jedi are mostly forgotten, and the only remnant of their passing is the Empire. It stands to reason that the idea of reintroducing the Jedi would not be well met.
Now RoTJ tells us that Luke destroyed the Emperor and paved the way for a new Jedi Order. This is the general idea in terms of how we, as fans, see it too. But if you strip away what we’ve been told, and look at what actually happened, RoTJ tells a different story. If Luke had had a decisive victory over Palpatine - and I mean a victory that would’ve actually resonated publicly - then it would be fair to assume that the galaxy would’ve happily embraced a new Jedi Order with Luke at its head.
But Luke’s ‘victory’ had no real-world repercussions. There’s no way he could’ve told everyone that Vader had been his father and that Vader had turned out to be a nice guy. Luke would’ve been lynched. All he really could’ve done was claim to have killed the Emperor himself in a way that definitely thwarted Palpatine’s potential escape from the battle. But this would’ve been a lie. Palpatine’s death was a lucky but unintended consequence of Vader’s change of heart. Nor is it clear that Palpatine (and Vader) wouldn’t have just been blown up with the Death Star anyway.
I just think Luke should’ve definitively killed the Emperor in a sense worthy of public acknowledgement, even if only by virtue of the whole episode occurring separately from the Death Star and with a measure of spoken intention on Luke’s part (ie Luke saying that he intended to confront the Emperor when he shared his plans with Leia instead of the whole “I just have to save Dad” bit). That way he would’ve been the guy who truly saved the galaxy - not just the guy who saved a war criminal’s soul and escaped to keep the old religion alive for no good reason. This would be a worthy springboard for a new Jedi Order as well as a satisfying conclusion to the whole ‘only hope’ thread of the previous films.