Diagnosing is outside the scope of practice for RPhs. As ignorant as some may be, diagnosing someone is MUCH more complicated than your average/lay person can imagine. Just use a reference like Epocrates for some fairly common skin conditions/diseases and go under the "differential diagnosis" section; you have to be trained not only to know what objective & subjective signs & symptoms to look for, but also what is missing/rule out other conditions in a fairly quick & critical manner. Sure the treatment is often very similar but like others have mentioned, there are TONS of obscure conditions/diseases that are not common & we are not trained to evaluate the root cause(s) or even have the means of production to do so (labs, tools, clinical skills, etc.)
Contrast to how RPhs can easily compare & contrast (differential) 1 drug class vs. another for a given disease state and provide insight as to which drug is best catered to a particular individual given various comorbidities (we are trained much more extensively @ doing this...(at least some of us ><)...weighing benefits vs. risk for drugs, having insight on the appropriateness of the dose (labs needed often), kinetics, dynamics, interactions of course, & hell, even dose form). Recurring theme being insurance/$$$ as an obstacle; most RPhs are well trained enough to work around the BS of insurance & at least make drugs affordable albeit with some compromise with what is optimal/ideal
*Look into collaborative practices (contracts); some of them do provide RPh opportunity to perform such tasks as taking labs, changing doses, changing drugs, etc. Honestly not so optimistic about these...
