Rey didn't kill herself, and she also didn't turn into the "Empress." Yet you're absolutely certain that the Empress scenario would've played out if not for Ben being there (and being redeemed). Based on what?
Based on the "rock rolling down a hill" principle.
Maybe the only reason you didn't see her turn the lightsaber on herself is because Ben showed up.
Your entire thesis is summed up with a whole series of interconnected "maybes" that literally go against the trajectory of every scene that you're offering as proof of your interpretation.
Nobody knows, and one can only *pretend* to know.
I appreciate that you're admitting that you're literally pretending that all of these made up scenarios that would have completely invalidated Ben's redemption with no actual basis for those scenarios to occur. I have a feeling that that's all I can hope for at this point, but I'll take it. "But you're pretending too Khev." Well, there are different levels of "pretend." My assumption for how things would have played out is the common sense take that if you see a rock rolling down a hill it will simply continue rolling until it reaches the bottom of the hill. Your take *demands* that you inexplicably assume that the rock will stop mid roll, turn around, and start rolling *up* the hill.
Yes I'm assuming that if Ben didn't arrive that Rey would have killed Palpatine and allowed herself to be possessed on the off chance (her only chance) that she could still maintain enough control of her own will that she could order the Sith fleet to stand down and spare the Resistance. *That* was the literal scenario that Palps presented to her, she toke note of all of her options (or lack thereof) and *visibly nodded in compliance* after seeing no other way to help her friends. The rock was rolling downhill, every scene was moving in the direction that she would follow through had Ben not arrived so yeah, I'm not going to "pretend" that every moment building up to that was a lie and things were about to do a complete 180 just so that I can maintain that the movie was "stupid."
You're free to believe or assume whatever you want obviously but you're literally fabricating "maybe" scenarios out of thin air that nothing in the film even hinted at just to maintain the narrative that the movie sucked. More power to ya if that's what you prefer but I'm not going to recontextualize that actual movie into something else just to turn it into something lame.
Without Ben there, Palpatine still would've stupidly told Rey his plan, so slicing him with a saber and becoming "Empress Palpatine" would still make no sense for her.
Yes it literally would have. See above.
also wouldn't have the option to reflect any lightning back at Palps because the "Dyad" needed to be united there (apparently) for him to level up and gain those lightning powers. So what would she do?
Throw out as many "apparently's" and "somehows" as you want as if it is ridiculous for there to be magical powers in a fantasy story (that were "apparently" always allowed until now) but at least those were elements that appeared in the film's on-screen narrative and weren't simply made up to twist it into something else.
As far as I can tell, Rey's options were: 1.) slice Palps and do his bidding exactly like he wanted, or 2.) kill herself and leave him no viable Force-user body to be his new meat puppet. Why the hell would she choose the first option (as you insist she would) since the second option would actually prevent Palpatine from getting what he wanted?
Option A gave her a chance to have some control over the fleet and save her friends. Option B would do nothing except piss him off further. "Ha ha, I'm killing myself, you're stuck as a zombie crane puppet (until you simply sire another Force sensitive offspring.)" "Hmm, so be it. Okay Admiral Pryde, remember when I told you to destroy Kijimi to get the point across? When your fleet leaves wipe out another 10 planets please because this ***** just pissed me off." Making Palps mad isn't a "win." Far from it.
Why not? Lando didn't leave Pasanaa on the Falcon, and he didn't need the Falcon to show up *on his own* at the Resistance base. Why would Kylo's turning influence Lando's desire, or logistical capacity, to rally the galaxy? That doesn't add up.
Ben stays evil:
Ignores his mother's call, kills Rey. He either blows up the Falcon (very easy to assume he'd want to take out his rage on Rey not joining him on the nearest target, ESPECIALLY knowing that that rat bastard Finn was nearby screaming her name.) Rey doesn't get his TIE's wayfinder, provides no way for the Resistance to reach the fleet.
Yeah I'm gonna go out on a limb and assume that Lando buzzing Republic planets in a pleasure yacht broadcasting "follow my non-military craft into battle as I blindly search for the Sith Fleet with no coordinates" wouldn't have quite been enough to do the trick.
Didn't Leia catch her son's attention by surprise, and *that's* what made him pause. Then Rey stabbed him. Kylo was still evil when she stabbed him, right?
I guess your view is that Kylo was already redeemed when Rey headed for the TIE. But my sense is that he didn't turn back to the light until the Han interaction. Rey left him recovering and took his TIE *before* that conversation with Han.
I have no problem saying that Kylo's turn began with Leia. Or do you really believe that he was "still evil" at that point and if Rey hadn't caught his saber that he would have what? Recomposed himself, apologized to Rey for the awkward pause and then fumbled around for his saber hilt at his feet before simply picking it up and resuming their duel?? No way, lol. He was done. His fight against the Light was gone. Now I do believe that at the point he was pretty much an empty shell and not ready to hop in an OT TIE (that "somehow" had a hyperdrive, grrrr) and rush off to Exegol. Rey's healing and Han's appearance definitely played huge roles in filling him with hope that he *could* benefit the Light in a significant way but him forsaking the Dark absolutely began with Leia's call. I don't see there being a viable way to interpret that scene otherwise.
Let the fame, fortune, and ladies just funnel my way. 
