Modern medicine has failed to move into the era of subtlety and small problems and many people suffer as a result. Fitness nerds and general non-scientists fill the gap poorly so we get a ton of guessing and anecdotal evidence and likely a whole lot of bad advice.
Doctors won't say there's a problem until you're SICK and usually pretty late in the process when there's not a lot of room to make improvements.
At the same time, doctors won't do anything if you're 5% off optimal, but they'll happily give you a medicine that improves one symptom that's 50% off optimal that comes along with 10 side effects. Although unless you're dying or have something really straightforward wrong with you, doctors don't do much at all besides giving you a sedative and or a stimulant.
Doctors don't know what to do with small problems because they're barely studied and the people who DO try to do something don't do it scientifically.