Or maybe Provide the updated Lore and those who don't want it can choose to ignore it, thus both gets what they want. There is far too much One group does not want something so nobody gets it happening in 5e.
There are two issues with this, though, one practical and one aesthetic.
On the practical end, providing this takes work, and D&D is a skeleton crew. Everyone on staff has quite enough to do without adding "Keeper of the Faerun Timeline" to someone's list of titles.
But further, it's clear that the D&D team wants to avoid setting up one chain of events as the "official" version, artificially elevating its status to The Way Things Really Happened. Because what this does is subtly de-legitimize whatever decisions you made at your table, and they don't want to send that message. The furthest they're going to go is suggest that
maybe the things going on in this other campaign had an effect on this one, but not so strongly that it won't work if that doesn't ring your bell. It's not a cop-out; it's a gift of empowerment to everyone's table that their version of Realms history from here on out isn't a poor shadow of the "real"* one.
So if that feels like a slap in the face to you ... well, I'm not about to yuck on your yum, but I have a hard time sympathizing with a point of view that's
insulted by a message of "Your vision is no less important than ours." Do the hardback campaigns happen in chronological order? They do if you want 'em to. What are the Red Wizards up to these days? You tell us. And with this comes a subtle, but important, subtext that there will no longer be "correct" answers to these questions that That One Player who knows all this stuff better than everyone else can use to cudgel all the other players at the table.
I mean, I can't tell you how to feel about this, but I'll tell you how it feels to be on the other side of it: lousy, is what. There's a reason metaplot fell out of fashion in a hobby that's supposed to be about the stories
you tell; there's no way to establish "official" ongoing lore without it running roughshod over someone's campaign and rendering it less important by comparison. The Spellplague was just the most egregious example of this (Hey, was your campaign set in Starmantle? Oops, we just wiped it off the map), but it's inevitable even if you don't ruin everyone's day with a Realms-Shattering Event. Which means that, unfortunately, there's no way to make everyone happy with this. WotC has recognized (rightly, to my way of thinking) that arbitrating certain kinds of canon
is itself a problem, and they're not going to do that any more, and there's no way to both do it and not do it. Given that, I think they've threaded the needle pretty neatly here.
*Which, Frank Miller's kind of a wangrod, but there's perhaps some helpful perspective in his famous answer to a fan who asked if the events in
The Dark Knight Returns "really" happened: "No. It's a comic book."