I saw std::result_of is being deprecated in C++17.
std::result_of deprecated in C++17?
T.C. already provided the obvious link, but perhaps the most horrific reason bears repeating: result_of involved forming the type F(Arg1, Arg2, ...) not for a function of those types returning F but for a function of type F accepting those types. (After all, the return type is the result of, well, result_of, not the input!)
Aside from the adjustments associated with forming the function type, the only difference between the two is syntactic.