One supposes that it was the purpose of the old-fashioned coronation ceremony to impress upon the recipient his importance in a certain context, and of his acting henceforward on impersonal motivation in the best interests of the territory of which he now became the representative and agent, without being led astray by the merely personal. This was made as impressive as possible so that he would not forget about it in the future.
And it is not irrelevant that the whole thing was supposed to place the royal person and his territory in relation to something outside of society, which was supposed to be run in accordance with a divine purpose. Cf. Land of Hope and Glory, performed on occasion at coronations, "God who made thee mighty, make thee mightier yet".
Fifty years ago I knew someone who read history at Oxford, and at her interview to determine whether she would get a first or a second, she was asked to discuss "the divine right of kings". I am sure that even then one was expected to make this idea sound ridiculous, and perhaps she failed to do so, as she was an old-fashioned Christian.
Nevertheless, I am sure that this reference to an outside context conferred some psychological advantages on the anointed ones.
The present Queen certainly seems to have a sense of divine mission and, not long after her coronation, made a speech to the nation in which she promised to consecrate her life to the service of the Empire. She has always fulfilled her role, as she saw it, impeccably, although this has not preserved her from criticism as cold and unemotional.