The airliner on final approach,traveling at 160 knots, flaps down, weighing 300 tonnes, can not take drastic avoidance procedures without stalling the aircraft.
I do not see that as an excuse to avoid a mid air. If you miss by one millimeter you miss. Weight has nothing to do with this, as the planes wing areas match the weight. However size does, as obviously it cannot turn a radius smaller than itself. Airliners are much more maneurvable than you apparently think. Loops and rolls have been done with many models. Besides per Part 91 they are required to avoid other aircraft. Sitting in your captains seat watching is not avoiding.