Immune disorders like MS. The immune system attacks the persons own tissues. It’s the inflammation that causes the damage. Prevent inflammation and you stop the disease.
Sure, the immune system is at fault, but it’s the inflammation that causes the damage. Since we don’t have great tools to tweak the immune system, if we prevent inflammation, we can stop the disease.
I don't get why you're so resistant to the idea that sytstemic inflammation (not gingivitis) can simultaneously be a symptom of one condition and the primary causal factor in many others. The article gives plenty of examples of conditions where inflammation does seem to be the root cause. It feels like you haven't read it, in which case I highly recommend doing so. It's quite educational and not not at all biased towards a big-pharma solution.
The article also gives sound reasoning for why metabolic stress, i.e., overeating, eating crap and not exercising, could be the most common cause of chronic inflammation. I would guess that psychological stress is another big factor given it's known ability to exacerbate autoimmune and inflammatory conditions. So the cure for most cases of chronic inflammation is going to be the usual mix of diet, exercise, sleep and stress management. We already know that these are the most effective preventative measures against age-related diseases and this research gives us a better understanding of the underlying mechanics.