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?
Also it’s important to clarify that leadership and management are different things.
Good leaders keep a team working together, motivated, going in the right direction - good management ensures a team prioritizes the tasks involved in going that direction.