@Warhead
This is the link to what I believe is the current accession standard for entry into the armed forces:
http://www.esd.whs.mil/Portals/54/Documents/DD/issuances/dodi/613003p.pdf?ver=2018-05-04-113917-883
Pages 42-43 are of interest.
The DODMERB medical history (with questions such as: “have you ever had or experienced X?”) and medical exam essentially establish the status of certain conditions. DODMERB Qs or DQs relevant to the standard. Each individual Service then has the option to waive the DQ, according to its current policy. Some things are never waived. Some are.
The Services have different waiver policies, because they have different missions, operating environments, gear. Army may waive Condition X. Navy may not.
The driving reason behind these high accession standards is quite simply, unit readiness. In forward deployed situations, where physical and mental stress is high, sleep is minimal and erratic, and operations are far from hospital-level medical treatment, people need to be as healthy, fit and free of pre-existing disease/condition/syndrome as they can, so they do not impact the unit readiness. They have to be counted on to contribute, and not be a distraction or a burden.
I have often commented here that those who want to serve, but are medically barred from uniformed service, can work for the “ABC” agencies as analysts, operations planners, logistics specialists, cyber warriors and other critical jobs. Google “CIA college programs,” as one example. If you can’t be a door-kicker, have the door-kicker’s back.