I have had several times seeing fellow pax has tight connections at IST due to our flights being delayed at origin - there were ground staff by the gate helping PAX to get to the connecting gate.
It happened to us once - our flight to IST was 2 hours delay due to snow and when we got out of the bus (bus gate) there were gate agents with various destination signs and we found ours and he walked us to our connecting flight.
Also we have never get BPs with our connecting gate printed on it on when we flew TK, LHR T2 doesn't publish gate number until 40 minutes before schedule departure.
I guess OP's friend had enough time to connect so TK sees that it's her fault because she didn't double check the connecting gate.