It sounds as though you have never given them a reasonable trial yourself. In the ‘pushing off from lights’ example you give, I keep my left foot clipped in. It doesn’t matter which side of the pedal the right foot contacts as you set off: you can clip in down the road if you want to.
Your assumption is... well, just an assumption, and we all know what they make, don't we?
I have tried them at length myself, and as a retired professional cycling instructor (advanced road skills, off road skills, nav, SAR, defensive tactics, first aid, maintenance....) with accreditations from two internationally recognised training bodies I have had dozens, perhaps even hundreds, of students through my courses with them - in every case they have proven to be less optimum than their fellow students who use one standard or the other.
The difference may offtimes be as little as a fraction of a second, but the difference is nevertheless there -
every single ride brings moments where the wrong face is presented to the riders foot. An adept rider may be able most ot the time to wiggle and jiggle and take but a moment to correct that, but thats in nonetheless a moment that other riders don't have to take. There's a reason why skilled, high level, professional or competitive riders use clipless
or flats but don't mix the two on the same device - if there were the slightest advantage you can bet riders in all of those categories would be all over them.
In your case you merely have a correlation of 1 to guide you.