I highly disagree. Junior developers will end up being Senior developers. How? By encountering advanced topics that aren’t taught in school.
My code base now makes heavy use of Inversion of Control containers. I would never revert my code to the old way because a junior developer had issues groking IoC. Instead I would take them out for a beer after work and discuss it. The more the junior dev learns the less hand holding needs to be done.
Here’s a blog post discussing this very topic.