I know this is suppose to be self-soothing for a managers ego, but unfortunately you are responsible for their failures if their failures result in projects going over budget or over schedule. You are responsible for creating an environment in which they can thrive AND also not f-up momentum for others. Thats a tricky task with a lot of nuance.

At the end of the day, as a manager, you are responsible for the teams success and failure. You don't really get to say "sorry we delivered late and/or over budget, a single contributor on our team is failing to execute well and thats not MY problem". A manager is responsible for a projects failure or success which, yes, means being responsible for employees who seem to be failing at the task.

What being responsible means is the more complicated question completely brushed over in this article. Do you fire them? do you 'create a better environment' - how and how do you do it without impacting the team, projects, or budget.

Being a manager is an extremely nuanced social and political task that i dont think a large majority of people are skilled to do. Being highly technical or having decades of experience doing the technical part of the job will not prepare you for managing people, unfortunately.