There is at least one valid reason to do what GP suggested regarding 1:1s in my experience:
If an employee is having an issue that they don't want to put in writing (or you sense this), oftentimes a one-on-one is the only way to coax it out. Particularly if they have an issue with leadership, HR, other managers, etc. Decent managers are also using 1:1s to make sure their employees are treated well in the org as a whole.
But I recognize the 'decent' is doing some very heavy lifting in that sentence.
Right. As a manager I'm invested in seeing the employee grow, develop, and have a fulfilling life. It's not 100% altruistic on my part, as a happy employee who is motivated to improve is better for the company. But I also care about them as people. Thus, the 1:1 is their time to drive that. My role is to help guide and coach, but they know themselves best.
However, another part of my job is to spot larger problems. That's an exercise in pattern matching. While you're talking I'm matching to keywords I've picked up in my travels. Other meetings, 1:1s, etc. Maybe there's a problem lurking down the road that's only visible if one assembles these disparate data. Sometimes those are problems for the employee that they themselves don't realize as you suggest, other times it has no direct connection to them but they're key to identifying the issue. That last part is why I don't agree with getting rid of 1:1s altogether.
If an employee is having an issue that they don't want to put in writing (or you sense this), oftentimes a one-on-one is the only way to coax it out. Particularly if they have an issue with leadership, HR, other managers, etc. Decent managers are also using 1:1s to make sure their employees are treated well in the org as a whole.
But I recognize the 'decent' is doing some very heavy lifting in that sentence.