Promotion vs. career change
To make things clear, we have to start with the management concept. When a technical expert becomes a manager, it’s not a promotion, but a change in career. Being good at technical aspects doesn’t guarantee that you can be a good manager because you need a different set of skills and attitudes for management. In fact, many people aren’t really comfortable having management roles and prefer to remain technical – we’ve been ruining their professional lives by forcing them into those positions.
A better way is to let technical people remain technical and seek other ways of promoting them, while in parallel investing in recruiting and nurturing other people for management positions. The latter can be enriched by undergoing higher education in (project) management as well.