That's just one example. There are multiple ways to approach scenarios, or skip them entirely, that so dynamically effect the story. There are several times you discover a "base" for a group and they can be an ally, an enemy, or an ally you betray. To see all the options and paths there can take 5-10 playthroughs alone. And that's not counting how you go about it, who you kill or spare, whether you pass with raw persuasion, or steal something hidden that gives you a free pass. And again, that's just one more difference that can happen in a playthrough out of many.

They clearly put a lot of effort into "the way to play is the way you play" and it shows"