> Magnesium? Its widely known that magnesium is used by the body lol

Who disputed this?

> What they “doubt” is that it can be absorbed through the skin

The science is helpful. Magnesium sulfate is absorbed less effectively than magnesium chloride. Of course, you're not eating the amount of Epsom salts one dumps in a bath.

> And it is studied btw - problem is there are countless on both sides

This is why meta analysis exists.