For things that can be handled by quick research online, and things that don't necessarily need a doctors approval (e.g. Should I take ibuprofen or acetominophen?), seeing a doctor is overkill. But for most situations, it's not that simple and a doctor, especially one who knows your medical history, would be very useful in determining if something is good or bad, what the risks may be, what complications something may have with a medication, and so on. This is especially true for a less common disorder or disease.