It's because movies are typically optional viewing when it comes to understanding the main story. He's canonizing the key parts of the Boruto movie by drawing them out.
The fact that the key events of the Boruto movie are being drawn out and the last never was tells us all we need to know about which movie was filler and which one wasn't but that's a discussion for a different day.

The fact that the key events of the Boruto movie are being drawn out and the last never was tells us all we need to know about which movie was filler and which one wasn't but that's a discussion for a different day.