3) To go with the consensus. This has to do with protecting oneself AND looking good.
Other than that, the word in the medical community is out if any M.D. does not diagnose and prescribe according to "The Book" they will be blackballed and subject to possible license revocation by the American Medical Assn. This is what is drilled into them in med school.
All this allows the drug companies to come in and take charge of WHAT is prescribed. The AMA and the FDA work hand in hand.
To sum up, M.D.s practice in fear of losing their hard earned and costly credentials.
Obviously, the new M.D. in 56756's case was new and energetic, then consulted the diagnosis book and maybe talked to an associate and figured she'd better stick to the straight and narrow.