Too Long; Didn't Read
Nowadays there is a natural progression for senior software developers (either in startups or more corporate style companies) to make the jump from their current technical role to a more leadership/management oriented role. This progression is usually motivated by several needs which arise from the evolution of the company/team/product and require the senior dev to dedicate his time to training/onboarding, planning/road mapping and leading the team, contributing to more macro level decisions and coaching while becoming less and less involved in day-to-day engineering activities.