Drizzt Returns! New RA Salvatore Forgotten Realms book 2018
It's both, really.
With 4E, WotC decided to start things off with yet another Realm-Shaking Event (RSE). It got rid of some locations on the map -- some of which were actually interesting -- and replace them with sections of another map that no one had ever seen, and cultures and cities that had their own disconnected history that no one had any familiarity with. All in the name of explaining the presence of races new to 4E.
They then jumped the timeline ahead a hundred years, but none of the existing cultures changed during that time. Cormyr was still a feudal kingdom, just with the noble family tree having a few new entries. Sembia was still a plutocracy, Waterdeep still a big sprawling metropolis, Candlekeep still an isolationist library-slash-monastery.
There was this gigantic worldwide catastrophe, that fundamentally changed how magic worked and threw in elements that could have had global effects (like the Plaguechanged and Spellscarred), and they did nothing with them.
AND!
Salvatore took all of his iconic characters from his entire series of books, then killed off all but one. Some had interesting send-offs, others were really disappointing. And then after one book of Drizzt being all angsty (again) and hooking up with a goth bondage chick, suddenly all (but one) of the old cast gets reincarnated. Why?
If he wanted all the crew to be running around in the 'current' time, he could have taken a cue from Cordell's Plague of Spells and had them hit by the Year of Blue Fire and jumped ahead a hundred years or so (either a literal time-jump, or being in suspended animation the way Raidon Kane was).
So, yeah. In 4E, everything changed but nothing really did. In Salvatore's books, everything changed but nothing really did. I'd say both are to blame in their own ways.
And yes I'm salty about it.