Can we increase the iterator without the function? C++11

I know we can use advance() function to increment the iterator. We also use iterator++ to increase the iterator by one position. Why we cannot use it+=2?

int main()
{
    list<int> l1{1, 2, 3, 5, 6};
    list<int> l2{2, 6, 8};
    auto it = l1.begin();
    advance(it, 2);         //works
    it++;                   //works
    // it+=2;                  //not work
    l2.splice(l2.begin(), l1, it);

    for(int a: l2) cout<<a<<" ";
    cout<<endl;

    return 0;
}

You can run the above code here