Conduct good Sprint Planning is not so easy in reality. There is a lot of misconceptions and anti-patterns around it. A lot of Sprint Plannings leads to unrealistic or useless goals, overcommitment, and Sprints without any Team ownership.
Self Managed, independent, cross-functional team. This sounds awesome, but in reality, it is hard to achieve. A lot of teams are passive, non-pro-active without any intent to become self-managing.