WebMD is just a website with information pages on health topics, not a program or custom response, is it not?
I think that there is a future that it may be a reasonable first step for people with restricted access barriers, but at this stage its too much of the wild west to be using it for these higher level cases.
But regardless i dont have specific information to present you, i woild argue the amount of people that have committ suicide after interacting with LLMs rather than seeing a mental health professional would be a fairly relevant example though.