Note that cout.tie(0) and cerr.tie(0) actually do nothing. What this does is it ties an input stream (e.g. cin) to an output stream (e.g. cout), so that if you cin a variable, it flushes the output beforehand. This should make sense, because otherwise the following code will be very confusing to beginners, because it won't prompt:

#include <iostream>
using namespace std;

int main() {
    cin.tie(nullptr);
    cout << "Enter a number: ";
    int x; cin >> x;
    cout << "You entered " << x << '\n';
}

but tying cout/cerr (and clog as well) to nullptr or 0 do nothing, because they're not input streams