Those benefits would have to be specific instead of a general healing potency. It had to work for migraine and not work for diarrhea.

Same way how "eating vegetables is healthy" is only a broad approximation. It does certain things, that are useful in certain circumstances, those circumstances being largely general unless one has specific medical conditions when not, such as undigestible fiber cleaning out the guts (not a good idea for Chron's), such as slow digestion meaning a slow insuline release (useful in general for most modern people, not so useful for eating directly before a hard workout), and so on.

Meditation doesn't detach from reality. Where did you get this idea from? It detaches one from one's interpretations of reality. Like you meditate and hear a sound. It teaches you to not instantly go and think "hey, that is a dog barking" and thus replacing the experience of a sound with a concept, with a mental category, but simply experiencing the sound directly without attaching any label to it.