Luke is the one with flashbacks, yes? This isn't enough information?
We see one of Luke's flashbacks in TROS, back to when he was training Leia and she had her own vision. We see several in TLJ -- two from Luke and one from Ben/Kylo -- of different takes on The Fateful Night™ when Luke saw how far down the Dark path Ben had gone and contemplated killing him, plus, once the truth came out, the extension showing the devastation to the academy and Luke's teachers and students. We saw another angle of that last in TFA. Those are all just snippets. Less than an hour of in-universe time. The destruction of Luke's academy happens only a couple years before TFA. Luke training Leia was presumably somewhere around the time he shows up in The Mandalorian.
What I'm talking about is that, between those, the Aftermath trilogy, the Shattered Empire comic miniseries, Bloodline, the Rise of Kylo Ren, the coda of the Rebels finale, and, now, the Mandalorian, we have seen a portion of the five years after ROTJ and the five years before TFA. We still have a twenty-year information desert between with only one too-scanty oasis of Rey getting left on Jakku and her parents getting killed (about three-quarters of the way through that desert). Writing For Dummies: If you end one chapter with the hero at his apex (Luke confronting and defeating the ultimate baddie) and start the next with the hero at his nadir (Luke vanished into self-imposed exile), with no explanation
at the time, but dropped in asynchronous tidbits here and there later in the work, that's... a choice. Cloud Atlas sorta does that, and it was liked by some and hated by others. It's not a choice that equals broad appeal, as it's a choice that directly contradicts a clear narrative -- which the films largely had up to that point -- the way a brick wall across a freeway contradicts your car's momentum.
I know you have your own opinions on the matter, but even if
you personally like it, it is objectively bad writing to go from one numbered installment of a story to the next with such a drastic and discordant jump, and then fill in the missing information in dribs and drabs drawn out over many years, especially when there had been straightforward narrative progression before. I'm not going to ding George for starting in the middle, when he only ever intended to do his one Flash Gordon homage and then go on to doing other things. Even if I take issue with his revealing in the PT all the twists of the OT, I can't argue that, when viewed 1-6 consecutive, it's a clear narrative, even with the time jumps. At the end of ROTS, not everyone was happy with Palpatine's new Empire, and in ANH, the first line we see is "it is a period of civil war".
I know you think the jump from 6 to 7 is covered perfectly well in saying that Luke has disappeared and a new group is stepping into the boots left empty by the Empire, but it really isn't. It... just isn't. I'm not saying we needed to be pandered to -- just that a
little bit more information was needed going in, and preferably seen, not told. The New Republic is entirely jumped over. Thirty years of governance gone before we ever knew them or why the First Order considered them "loathsome". Basically, we needed Bloodline before TFA. Everything else would've been fine. No Luke (he was out with Ben), Leia's son only spoken of, not seen. New Republic in (in)action. Discovery of the First Order, if not by name. Leia's rep trashed, and her quitting in disgust and forming the Resistance. Could still fill in the missing generation later, even though I'd much rather have seen more of it -- but that goes back to my whole gripe that there needed to be more episodes overall in order to tell the full story, rather than the Cliff's Notes version. But
at minimum we needed to see the new normal established at the end of the previous episode turned on its head, not come in an act late, after it had already been.