Molarity is arguably the most intuitive descriptor for the "number of particles". But freezing point depression dependence on solute concentration is commonly described in textbooks as a function of molality. The same textbooks make it seem as if freezing point depression formula was determined empirically, in which case, it should take take only a few corrective factors to change it into a dependence on molarity. (In fact, I wouldn't be surprised to learn that some correction factors should be used to make the currently formula more accurate. That is often the case with empirical formulae.)
So is it really the case that using molarity would make the formula dependent on solute nature, or was molality used for convenience?