I think this article does a great job at conveying the new skills you need from a work-completing perspective as a manager, but there's another aspect that is much more subtle and long-term: being a guide for other people's careers.

I've seen dozens of people start managing, stop managing, change roles (including myself), etc, and there are two extremes that stand out:

1. Management out of necessity. They became a manager because they wanted to solve a problem that is too big for them to solve alone, and no one else was willing to fund it. So they got headcount, hired a team, and set them to work on solving the hard problem. But the problem they're solving is the only focus. This manager tends to have an elite team of low-maintenance engineers who just get things done. They are very effective, but eventually when those reports start asking questions like, "how do I get promoted? What's the next step in my career?" their manager has to suddenly learn this new set of skills or risk losing their highest performers.

2. Management to be a mentor. They became a manager to help other people grow. Sure they are solving problems with the team, but this manager spends the time to help higher-maintenance engineers grow their own skills. This is time-consuming, this can be frustrating, progress is going to be slower, but eventually you can reach very high throughput, and also feel very accomplished knowing you helped someone else reach their potential. This, however, has to be balanced with not moving so slowly that you frustrate your top performers.

There's nothing wrong with either of these extremes so long as everyone in the manager-report relationship knows what to expect, and many managers will be between these two extremes.

The main tl;dr takeaway is: as a manager, you are not just responsible for people's tasks, you are responsible for their career. Managers need to take this seriously and address it head-on to build those skills before the first time a report asks, "so how do I get promoted?"

As another commenter mentioned, the first role is Vision + Leadership, and the second role is more like Support + Mentorship.

Personally I would love do the first, and the second one feels more like HR should do. Of course, HR doesn't have the specialization needed for that, but maybe they should expand into that? HRO - Human Resource Optimization.

Perhaps these two roles shouldn't be conflated into a single position?

The only career goals I want my manager to be responsible for is to not be in my way. I tinkered with my PC since I was young without my manager. I decided to go to Computer Science without my manager. I got my degree without my manager. I got my first job without my manager. I practiced lifelong learning without my manager. I ran my own company without my manager. I handled clients without my manager. I managed to find mentors without my manager. Etc.

There might be some people that need a nanny. I am not one of those people. My manager should be a proper valve between me and whatever layer he manages for and should not play stupid games when it comes to my career. That's it. He's a colleague. Not a mentor. I'm perfectly capable of finding mentors for myself, and if it happens to be them, well, kudos to them.