Yes. The military sets its physical standards based on decades of experience with MILLIONS of people. Medical problems that are minor in a civilian environment can become life threatening in combat, in isolated assignments, and in the very stressful conditions that accompany many military missions and training. Furthermore, when the military takes you on, your medical problems become their medical problems, meaning higher costs to the service.
They allow for waivers on the basis of further investigation of potentially high risk (from the above mentioned military perspective) conditions. For instance, a long scar could be from a previous compound fracture that leaves the bone or nearby joints compromised, or it could simply be from a long, nasty cut.
The military takes people based on
its needs. All the recruiting hyperbole and social engineering yakkity yak aside, what YOU want is secondary to their needs. I suggest that you wrap your head firmly around that concept now, before you swear your enlistment oath, because it WILL loom large and sometimes very unpleasantly during your stint. Otherwise, you will be a very unhappy camper.
Grace and peace,
BD