Sure, but the closer I stick to what is published, the less work I have to do in that area, and the more time I have to devote to other parts of the campaigns I run. I want the fluff I have in the books to do the work for me. It's an encyclopedia, an atlas, etc, that I don't have to spend time and effort in. In order for it to fulfill that function, I need to be able to reference it and just treat it as accurate. (Part of the reason I do this is I treat the multiverse as my setting, and use homebrew worlds as well as published worlds. I'm already making new worlds, so when I'm also visiting a published I world, I'm not interested in reinventing it.)
I have a bunch of 2e books. I have the 3e FRCS, which mostly agrees with the 2e books.
Let's say my official date of "canon synchronization" between my setting and publications is in 1371 (which might be accurate, but I'd have to look it up).
Now let's say a party went to Blingdenstone in 1371, and I used the 2e and 3e material appropriate for that synchronization date. I referenced them and ran the sessions based on what I found in the books. And now let's say it's 1374 in our campaign and I want to run Out of the Abyss. But their version of Blingdenstone assumes over a hundred years have taken place since then. It's really hard to figure out how to make that work. I've even considered shenanigans like some sort of localized supernatural time compression affect, but that honestly isn't really satisfying.
My simple experience here is that you can't add a hundred years of change, then shift some things back to feel more like they did before, and then expect everyone can just us it whenever they want. The problem is that there are already too many details for that. You have to keep things much more vague than the Forgotten Realms have ever been for that to work. Otherwise you end up with a mess that only works for people who either don't know or don't care about details, have no previous edition commitments, or who are willing to spend time using the new material as suggestions to inform their creativity rather than ready to go reference material.