Mentorship programs benefit everybody.
When a new engineer begins their journey on a team, they have a lot to learn in terms of technical skills and domain knowledge. During this phase, they need to ask many questions to get a better understanding of things around them. Effective mentorship programs can help, providing them with answers to their questions and speeding up their transition to becoming confident and productive members of the team.
I was a mentee early in my career and have since worked as a mentor multiple times. During these roles, I have seen and experienced things from both perspectives.