You can’t unknow something, sadly. On the exterior, nothing changed, sure, but the implications of like 90% of WoW history has been completely changed on a fundamental level.
Let’s look at Ner’zhul, for example. Without the Jailer, his is a story of a power hungry villain with just enough of a brain to realise a raw deal when he sees one. First he makes a deal with the Legion, then realises they’ll make him a slave and decides to back out of the deal. They turn to Guldan instead and Nerzhul gets betrayed. Then when Guldan goes off doing his own thing and the Orcish invasion fails, Nerzhul knows the Legion will come to punish the Orcs, and they’ll especially punish Nerzhul for backing out of the deal. So he does a hit and run on Azeroth stealing artifacts that lets him open portals to many other worlds, destroying Draenor in the process, hoping to go to a random world and escape the Legions wrath. He instead walks right into Kiljaedans clutches. KJ torments Nerzhul but ultimately gives him one final chance, creating a suit of armor, putting Nerzhuls soul in it, and hurtling it to Azeroth with some Dreadlords to watch over him and make sure he plays ball. From here, he perfects the Undead plague, begins his domination of Lordaeron, and manipulates Malganis into luring Arthas to Icecrown, to become the Scourges champion. Malganis is tricked and killed, as the plan was actually to use Arthas to free Nerzhul from the Dreadlords and the icy prison. And it works, to a degree, leading ultimately to Arthas overpowering Nerzhul and becoming the Lich King, creating his own citadel to conquer Azeroth from.
NOW we are to believe that this was all part of the Jailers plan. Even if we ignore the extremely contrived parts like Nerzhul backing out of the deal being part of the plan, and KJ not questioning how the Dreadlords suddenly came back with a Helm of Domination and an undead plague stolen from the Shadowlands, we still have some major plot problems. As the wearer of the Helm of Domination, Nerzhul should have been under the Jailers control. The Dreadlords were also under the Jailers orders, as they served Denathrius and Denathrius served the Jailer. Yet apparently part of the plan was to corrupt Arthas so that Jailer could use Arthas to… defeat the Jailers servants… what? This makes no sense. And the entire point of this was so that the Lich King could construct the Icecrown Citadel and the Forge of Souls so that many many many years later Sylvanas could break the hat, linking Icecrown to Torghast, and he could use the Soul Grinders from Zereth Mortis to… tbh I still don’t know what he was doing.
If that’s all he needed why didn’t he just use Nerzhul and the Dreadlords to build the citadel? Why did he need Arthas at all? Sure he couldn’t conquer Azeroth yet because he needed Argus to break the Arbiter so all the souls would go to the Maw (a plan that has its own slew of issues) but he could have just defied the Legion. Nerzhul already did as is, and KJs plot for vengeance was Illidan, which failed, mostly because of Malfurions intervention.
This went from a story that made sense on its own merits to one that is completely nonsensical purely because of the addition of THE JAILER PLANNED THIS THE WHOLE TIME MWAHAHA