Yep, that's a huge comorbidity, especially when you contrast that with the rates of alcoholism in the general population. That 45% for lifelong comorbid alcohol use disorder seems fairly standard across a number of epidemiological studies, but the average jumps to around 60% for ALL substance abuse disorders, not just alcohol. There is also a bit of a cause-and-effect thing going on, as people with relatively mild BPII can progress to BPI as substance use escalates, and the cycling of BPD can also speed up. Generally the more rapid the cycling the more severe the effect of the disease.
Stopping substances is indeed important, but it's only half the picture when dealing with bipolar disorder and many other mental illnesses. Dual diagnosis is seems to be often undertreated by many recovery programs, no matter what the stripe, method, or philosophy.
I have gotten sober by simply not using after some pretty brutal self-detoxes. When I have been unmedicated or otherwise untreated, I invariably went back to substances, and this seems to be a pattern with substance and comorbid mental illness, definitely including bipolar disorder. One without the other wouldn't work for me, despite pretty much taking the position that alcohol and drugs are off the table, for life.
I have encountered 12 Step "big book thumpers" (thankfully none at SR, at least not overtly) who view psych meds as meaning you are NOT sober, that people who do meetings and step work and follow the Big Book should need nothing else to address any mental health issues if they remain sober. I find that the reliance solely on a Big Plan without addressing mental health issues as equally important as sobriety to be similarly irresponsible, even dangerous. Untreated mental illness can, and often does, lead right back to the DOC.
Bipolar disorder responds extremely well to medication, but also has a notoriously poor rate of long term medication compliance. People like hypomania, and will often go "off their meds" to chase it. The LAST thing that population needs is to have another reason to stop taking their medication. Also, like the kindling effect of alcohol, mania seems to worsen every time it occurs, and cycling shortens. Of course there is overdiagnosis and overmedication, but there is also a lifelong pattern in many bipolar disorder patients of leveling out the moods with meds, feeling better, thinking "I got this" and going off the meds, and ending up back in the hospital.
Addiction is a highly complex state with a nearly infinite amounts of individual variations. It does not lend itself to a one-size-fits-all treatment method.