Teaching juniors can be more productive than coding. Being 10x by yourself is less good than 3x-ing a whole team. Even better, teach everyone to be as fast & good as you. Good teaching requires good communication and building trust.
Understanding priorities and goals is absolutely critical to making good choices while programming. Writing good code under reasonable deadlines in an organization necessarily involves a lot of discussion about what constitutes an acceptable solution, what doesn’t, how long it might take, how long is too long, what features are nice but not necessary.
Over-engineering, for example, is extremely common, and is caused in part by not correctly balancing goals and priorities with time budgets. It’s usually a symptom of mis-communication.
Can’t even count how many times I’ve seen a programmer go off the rails building stuff that wasn’t asked for, only to have a meeting several weeks later that invalidated weeks of work when the goals were clarified. (That includes me, btw.)
Making large changes and leading a group of programmers often requires a lot of convincing and rallying work along with the technical planning, sometimes much more than you’d expect. It also requires the ability to put yourself aside and allow others to contribute to the design, even when you think your technical solution is superior.
Getting promoted is, in my experience, most commonly a process of demonstrating to others that you listen well, organize well, work well with others, get things done under deadlines, understand and report what juniors are doing to management, budget well, internalize the organizational goals and contribute meaningfully to meeting those goals.
In short, it’s because teamwork is important.