As always, Chesterton's Fence applies to medicine.
Be very wary of anything outside of healthy diet, sleep, exercise, and relationships.
If you don't know why your body is fevering, don't lower the fever. If you don't know why your blood pressure is high, don't lower it.
We in the medical field vastly overestimate our understanding of human physiology.
And if you don't know why you have cancer, don't do anything about it?
Like, I get the point with fever (which is a known defense mechanism), but high blood pressure is a big problem in the long run and even if it's just a symptom, not doing anything about it is not likely to be the best move.
Humans evolved to reproduce as a species successfully, not to ensure the optimum survival of an individual. Not everything your body does is in your best interests: something that tends to be the best solution for long-term survival for a group might be entirely wrong for your specific case.
That's an overstatement. More than one thing can be true. What you said is valid, useful and mostly true, and so is what skepticalmd said above.