Pretty much every company I’ve been in or know of values a vertical trajectory instead of a horizontal one for its employees i.e becoming a manager nearly always means a faster salary progression than becoming an expert in one or multiple fields.
Why is expertise valued less?
The value of experience is logarithmic. You’re going to learn far less in the tenth year of doing something than the first year. Since management usually doesn’t start at year one, they are still in the part of the curve that rises faster.
Also, a lot of the value in higher levels of experience is usually management adjacent, like knowing what order to perform different tasks on a project and identifying when there may be issues beforehand. Someone who remains an individual contributor isn’t going to be providing value for technical roles adjacent to management.