It's true that many bipolar people have comorbid diagnoses. In fact, I believe that's true of most any mental illness. If you can be diagnosed with one, you can probably be diagnosed with more than one. That said, just because you're bipolar, for example, it doesn't necessarily mean that you have to pathologize every other aspect of who you are, as well. Just because you're bipolar doesn't mean that every last aspect of who you are must be explained as a bipolar feature. Everyone is different and nobody fits the DSM checklists perfectly. And you don't have to in order to be diagnosed.

When it comes to personality disorders, I would say a diagnosis is only meaningful if your personality causes you issues separately from your other diagnoses. For instance, I'm also quite reclusive. In my case it's not because of any social anxiety. I just don't feel the need to socialize much, if at all. I'm just happy being alone. I don't see it as a disorder, because it doesn't normally cause problems for me. Similarly, I haven't had the best childhood, but normally that doesn't cause me any issues either.

However, I find that in the context of bipolar episodes, sometimes things that were fine before become a problem. You might start to ruminate about things that you normally don't give a second thought to. You might have a much harder time dealing with stress than you normally do. At that point, some Pdocs start to get things backwards and claim that since you're ruminating about some particular thing or having trouble keeping your life together, that must be the cause of your issues. That bothers me because it doesn't make sense when it's bipolar depression that triggers the ruminating and that messes with your ability to cope, not the other way around. In my experience, depression latches on to all aspects of your life and twists everything until it starts to look like a problem, even if it wasn't before. You'll always end up ruminating about something. Similarly, it will wear you down until it's hard to cope with even the slightest problem. And since everybody has stuff going on in their lives, it's easy to point to that stuff and say that if you just fixed that, you would be fine. It doesn't work that way.

Besides that, the way I see it, everyone's illness, whether it's bipolar or something else, manifests through the lens of their personality. Your personality influences how your symptoms present. In that respect it can be useful to know a bit about your personality. Similarly, it can be useful to know a bit about your childhood, especially since some theories, such as kindling theory, would imply that childhood trauma can be a trigger for bipolar. It's also good to know what your stressors are so that you can try to minimize stress to hopefully prevent new episodes from starting up. But despite all that, I think it's important to remain focused on the real problem at hand, which in my case is the bipolar, and focus treatment on that. I prefer not to get sidetracked by other diagnoses unless they cause issues outside the context of my bipolar episodes.