It doesn't remove free ions (Ca, Mg, Mo), but it could possibly remove chelated metals (Fe, Mn, Cu, Zn) as the chelators themselves are large organic molecules. The evidence available is all extremely subjective/anecdotal, so you can't really draw any solid conclusions from it, and most of the people most adamant about it are talking out the butts.
It's only an issue if you force it to be, and if you force the issue, you're doing something wrong. I wouldn't worry about it unless you're going to be using a fresh batch of carbon diligently every two weeks, in which case there are better ways to go about chemical filtration.