One difference between puppies and junior developers is that you can discuss career aspirations with the latter. If you have juniors AND you can influence resourcing decisions in your company, then you can try to align the work given to the juniors with available projects that could best support their skillset / career development.
Not a dig to the parent post but in general, plenty of companies have "career development". What's lacking is the appropriate salary increases, which is why changing jobs is common.
