It's still valuable to share information about progress and impediments with the whole team. Alice and Bob may have some blocker that they've been communicating about, but Chris wasn't a part of those one-on-one conversations, so the standup gives him some valuable context about what's going on with the rest of the team. Maybe his work depends on something Bob was supposed to complete today that's going to take a few more days, or maybe he's encountered a similar problem before and has some advice, or maybe he'll remember the issue when something similar pops up later on. Alice and Bob would have resolved the blocker themselves, but this helps make sure the information is shared across the team in a way that simply moving cards on a kanban board wouldn't communicate.