As tobzalp says, there is a world of difference between traffic going the same way in the LHR sausage machine at slow airspeeds and opposite direction traffic in the upper air with a closing speed of almost 1000 Knots with no effective control and separation being applied.
Plenty background info in the D&G Forum to show why even the 'good old days' ivory tower controlling of LHR would not be applicable or relevant in the situation being discussed.