Here’s the answer from Adam Isgreen during an interview with PC Games:
PC Games: Compared to the remaining moderate requirements, however, you recommend 16 gigabytes of memory. What makes the definitive edition consume so much memory?
Adam Isgreen: This is due to the high zoom levels when more and more must be displayed on the screen. Here, much more memory is needed. If you play with a lower zoom level, it might work with less memory. This is the wonderful thing about PCs. People find ways to get it running on all kinds of machines.