I actually found the AMA, and this is what the question/answer was:
Like the original Baldur's Gate, will locations be broken down into sections or will it be like in DOS2, where you are in a huge terrain?
David: You're in a huge terrain, but between acts you will travel from one huge region to another.
So this seems to indicate that, for example, the city of Baldurs Gate probably won't be in more than a single act.
I actually agree that closing areas off due to story isn't a bad thing. And while I suspect some people may see this as a negative, I don't see anything inherently wrong with this design, either. Just different from the originals. But some people no doubt have expectations that won't be in line with this.
Link to the source:
https://www.reddit.com/r/IAmA/comments/fhk1u3/im_swen_vincke_creative_director_at_larian/
