I do, however, think it makes much more sense as a consumer tool rather than a doctor tool: if I've already gone through the trouble of making an appointment at a doctor, who I trust, I've either given up on trying to resolve the issue myself and will trust their prescription, or I have no idea how to approach the issue or symptoms I'm feeling as communicated by WebMD. Your value proposition is saving the consumer time and effort of booking an appointment to find out how to best fix a minor-medical issue they (or, say, their child) may have. Is that a sustainable proposition? I don't know, but it makes much more sense to me than as a tool to tell doctors how to do their job "better".
I'd imagine if you went the WebMD consumer route, too, once you reach a certain user-size, you'd have no problem partnering with pharmacies (or even pharmaceutical companies) to offer coupons for some OTC medicines in exchange for a referral fee, as is standard in the industry (a. la. GoodRx). Then you're providing value to the consumer in the form of recommending useful medicines, providing the consumer a way to get that medicine for a lower cost, saving them time and money spent at the doctor's office, and providing the pharmacy/pharmaceutical company a new customer.