The data protection officer—I speak as a recovering data protection officer—is tasked with certain specific outcomes but does not necessarily have to be a senior person within the organisation.
Indeed, in many cases, they can be an external adviser to the organisation. On the other hand, the senior responsible individual is a senior or board-level representative within the organisation and can take overall accountability for data privacy and data protection for that organisation. Once that accountable person is appointed, he or she can of course appoint a DPO or equivalent role or separate the role among other people as they see fit. That gives everybody the flexibility to meet the needs of privacy as they see fit, but not necessarily in a one-size-fits-all way. That is the philosophical approach.