It speeds things up, and you can get a leg up and a head start on the people who came before you. There's a reason we have coaches, teacher, professors, text books and mentors in life. To learn from someone(s) who already put in the work.
When we hire someone at work we don't set them loose, we give them a mentor. We invest in mentoring enough that we even have a billable code to bill time for mentoring a new engineer. We don't have time to wait around for them to try to learn everything on their own, we have clients waiting.