Because people develop ownership and entrepreneurship when they can take responsibility for their own development. Also, this responsibility makes people reflect more deeply on their own personal and professional growth. It encourages them to talk together about strengths and learning needs which also boosts collaboration. In addition, people working together know best what they and their colleagues need to develop.
Each year each team creates a development plan/proposal where they outline their need in terms of training and development in a professional and/or personal sphere and on an individual and team level.
Ask teams to take some time every year to create a development plan for the team and its individuals.
Define upfront the criteria for the development plan (budget, personal/professional development, timing, necessary output etc.).
You can consider consulting HR to make a template for such a plan.
Also, if you have several teams it can be interesting to ask them to present their plans to each other, receive feedback and then complete their plans.
The team is responsible for organizing all activities necessary to enacting the plan in coordination with HR.
When you want to encourage people to take responsibility for their own personal and professional development within the framework of a team.