Why has the central conflict of League, Demacia vs Noxus, been ignored for the last 4 years?
At it's core, the story if League was Demacia and Noxus fight too much, that's why the League of Legends was made, to stop their fighting (And even then, it didn't actually stop them from fighting).
All stories pretty much had something to do with those two countries for the first few years of League, and while there were some sidestories like the Bandal Mothership, the wedding of Ashe and Tryndamere to unite the Freljord, and one major event, the Noxian invasion of Ionia, the Demacio-Noxian conflict was the center stage. And those tensions rose to a fever pitch with the Kalamanda event. The biggest story arc League had ever seen, which was all tied to the new game mode Dominion.
But...that was also the last time the two nations were at conflict in the lore. And the few times the nations have shown up at all were just in champion lore (Sion rework), or as a tool for another country's lore event (Quinn's Journal). Since then we've had 4 years of silence while minor factions get the focus instead.
And now that the League of Legends and everything in the Journal of Justice has been retconned out of existence, that means so has Kalamanda. Meaning our central story of League of Legends, is a conflict that to this day, has not happened yet. The only people that Noxus has fought in the lore anymore, and the only war that is ever brought up, is the invasion of Ionia, which was SIX years ago.
I mean, don't get me wrong, the Freljord, Shurima and Bilgewater events were cool, but in the end, they're filler.
I feel like I'm watching the Naruto anime again. 4 YEARS of filler.
Heck, the two main characters, Garen and Katarina, haven't even shown up tangentially in any lore event since Kalamda, only making appearances in the non-canon cinematics. Where was Katarina when her sister was being guided into a Shuriman tomb by Sivir, and being transformed into Cass? I know that they're not very close, but still. Heck, it's been so long since they've been in the spotlight, most players who joined after the start of season 3 probably don't see them as the main characters of League at all, when back in the Journal of Justice era of LoL lore, it was pretty undisputed.