If leadership success is accepted as being critical to an organization's performance, why is so little support given to a leader on-boarding and early development?

If leadership success is accepted as being critical to an organization's performance, why is so little support given to a leader on-boarding and early development?

The Company support is very minimal for the new recruited leader. Some organizations assume that the individual will accept the responsibility for his or her own success as soon as he is recruited. Thus, the selection criteria is inadequate and focused too much on experience and job knowledge. There is no scope given to the Management to decide his job responsibilities, thus, making it difficult for the leader to start with his job.