A program that can be very confidently wrong while giving people advice that can mess up their life
Literally WebMD.
I think there's an assumption that professionals are always correct. They are not. Professionals are also heavily trained to "[try] to make you happy and doesnt know if [they are] telling you right or wrong, only that [they] shouldnt say [they don't] know."
You're also neglecting how bad health care access, and legal etc., is. Especially in countries like the USA where access to healthcare is financially gated and increasing extraction makes "go[ing] to a professional" not possible unless you wait >6 months to go somewhere that's a >3hr commute from where you live. WebMD, Wikipedia and chatbots can help to decide whether the >$1,000 and 7hr professional consultation is worth it, and if so be more informed going in so that the time is better spent.
That being said, poor healthcare can absolutely have worse outcomes than no healthcare. I do believe that is a minority of situations, however I also lack any hard evidence to really back that up. Do you have any?