Hi there,
I sort of know what you are going through, I've been told a similar thing once by an orthopedist. I work in medicine, I got my MD but I am a researcher in drug delivery...so, not a clinician. And I climb and get hurt a LOT.
But here is my view on climbing and doctors: the climbing population is too small and the problems we have too trivial to be a concern in the medical community. There isn't enough information. This is not an exclusivity of climbing, a lot of diseases, serious ones, are simply mind boggling and impossible to solve. Otherwise we'd be living thousands of years like super heroes. Rocks are hard, tendons are soft.
When seeking a physician, we need to adjust our expectations. Most climbing injuries lie in a range of "diseases" that the doctor simply has no tools to work with (drugs or surgery). If there is a fracture, an obvious problem, the physician can address it, if not, it's the time off routine, and usually, for some reason (don't tell me about poor vascular flow until proven so), soft tissue hand injuries take a LONG time to heal.
In your case, the doctor simply did not know what to tell you. There might be literature that links hyper mobility to some types of injuries, but I suspect those are dislocated shoulders, etc. I seriously doubt there is any evidence to the specific information he gave you, he linked his personal experience, something he glanced at some point, and tried to give you an explanation: so, from a rigorous point of view, he is not right (but he is also not wrong, he is giving a hypothesis). It does not help you anyways. If you are missing a leg, and I tell you so, it won't do much for you.
How I deal with my own propensity to injuries? I adjust training schedules, I cross train and I suck it up. Do not over train. Do you have excessive aches when running? Are you prone to overall tendinitis, random pains? Apparently I am, so over the years I had to learn to take longer breaks, I never climb inside the same 72h period, and you can climb quite hard giving longer rests.
Also, how does it feel around your medial epicondyle? I honestly think that guys who are more prone to injuries are usually the obsessive anxious climbers who want to do everything hard. Train hard on lighter things to then put yourself to the job in the routes. Learn from other sports, training routines, etc. Basketball players do not train by playing hard games everyday all the time. The body needs to heal.
ok, I wrote too much, bottomline
1- Your doctors could not help you, as is most of the time with climbing injuries
2- Do not be an anxious climber. Train wisely, do not be obsessive with movement. A hard movement 3 times that didn't work? Train harder on other things, proper campus, etc, and come back to it later.
3- Longer intervals
4- Find other sports you like. You will heal, and you will be hurt again: make sure you have other things to do.
5- If our docs could help us, they would. But unfortunately, if it is not a surgical issue (complete ruptures, etc) they can't offer much.
hope this helps a bit...