I’d say there are many people without the skills to be a top tier engineer. In fact I picked my IC to manager conversions based on their inability to progress as an IC but their empathetic and organizational abilities let them be a credible engineering manager. They weren’t great engineers but they were good enough to know what good work looks like. However the absolute best IC engineers that commanded the most money could easily have been a successful manager but enjoyed IC work more, and were much more valuable making engineering decisions than holding 1:1s and meeting with auditors. They were effectively matrix managers in many respects. That’s a much more rare skill, and you can’t mentor someone into being a top engineer. They’re born, and are born at the same rate as they always have been, and are there for much more rare as the industry and demand has grown.