It's really should not about ignoring the books.Personally I think the game teaching every single player and DM that they should ignore the books is an exceedingly good and important lesson. So them putting in the stuff about the "multiverse" and forcing DMs to learn how to pretend it isn't there is a net positive. Because the last thing WotC, I, or probably anyone wants is a DM who thinks the game has to be written to THEIR specific wants and needs.
That is a belief we need to drum out of DMs early and often.
It should be about teaching DMs to make their worlds diverse. Or play a game tailored to the theme specifically.
No one will love a homebrew setting more that those who craft it.
So if you don't let your players in the worldbuiding, your world must have a bunch of places for players to latch onto.
One thing I saw with every new DM who came to me is that their worlds were too narrow that some of the players didn't care about any of it and designed stuff that didn't match the DMs narrow vision.