Titles Of Nobility only mean what it says, nothing more...you people are reading tooooo much into it...
See anything pertaining to Kings, Queens, Nobility etc. from the definition below???

I rest my case.
DOCTOR:

1. health services somebody medically qualified: somebody qualified and licensed to give people medical treatment


2. health services dentist, veterinarian, or osteopath: a title used before the names of health professionals such as dentists, veterinarians, and osteopaths


3. education somebody with highest university degree: a title given to somebody who has been awarded a doctorate, the highest level of degree awarded by a university


4. somebody who can fix things: a skilled practitioner of something, especially fixing or improving something
a play doctor


5. christianity Roman Catholic theologian: in the earlier history of the Roman Catholic Church, an eminent and influential theologian


6. education teacher or scholar: a teacher or somebody very knowledgeable ( archaic )