As others have said I think it is important to fill in the form. Even from the point of view of there being a health problem during a trip, it gives the operator a starting point to go from (as well as information to pass on to paramedics/doctors etc) if required for further treatment.I just re-read the medical release form and it's pretty thorough. Our doc has signed off for me and my husband but it seems like a PITA to say "yes" to the individual questions. For instance "Are you over 45 and ... currently smoke ... have high blood pressure ... currently receiving medical care?" I don't smoke, don't have HBP but I am under the care of a doctor - and my husband has HBP but is under the care of a doctor and takes meds that keep his blood pressure in a safe range. So ... I don't want to check those lines and explain it to the kid at the desk of the dive op if my doc has signed the form. It all feels intrusive and unnecessary if the doc is saying I'm ok to dive. On the other hand, I think it's a good idea for the paramedics to know what meds I might have on board in case of an emergency, and that's stuff to keep on my medical profile on my phone, where it can be accessed without needing a passcode to get into my phone.
(here's a link to the form, for anyone who may be interested: https://www.padi.com/sites/default/files/documents/padi-courses/2.1.5 rstc medstate v201.pdf)
It can be very different outside of the WRSTC.
I don't know if it is still true, but when I was with UTD, their medical releases were only good for the specific class you were taking. You had to fill it out online. There was no doctor's statement. You had to fill in all the very specific details of your medical condition, including any prescription drugs you were taking, and UTD, not your doctor, would determine if you were fit to dive.
It all took a very long time, and their online system would not remember anything you had done before, so you had to do it anew for every single class you took. When I took the Ratio Deco class, I had just finished doing it for yet another class, and I was frankly pissed that I had to do it all again. When I came to the part where I had to list my prescription meds , which I had done a couple weeks before for the other class, I figured what they heck--this is a purely academic class spent entirely in the classroom, so I left it blank. A week or two later I was rooming with my usual UTD instructor (who was NOT the instructor for the Ratio Deco class) on a dive trip, and I came into the motel room to find him going through my toilet kit. He had been instructed to find out what my prescription meds were because I had not listed them on the online form.
If I found anyone going through my stuff without my permission, I would be seriously thinking about reporting them to the police as well as reporting the motel staff to the management of the motel for allowing access to my belongings without my permission.
If the instructor or UTD needed the information, why not simply ask why it wasn't on the form?