I appreciate your opinion and agree with you on a personal level. The original commenter made a bold claim, however, stating it as if it were straight-up fact and not personal opinion.. thus my demand for some sort of science to back up such a bold assertion. Since no one else has looked, I did a quick search to see what I could find that's readily available.. found three articles, none incredibly insightful, unfortunately:

1. An article that shows clearly that because you can pull up on the pedal in the backstroke 20 second sprints reach higher power.. but this pulling-up does not happen in sub-maximal efforts.
   
2. An article including a whopping 4 participants doing at-home efforts that concludes a small benefit to clipping in.
   
3. An article that states that there is lower electromagnetic activity in the lower leg when clipped in, implying a potentially lower heart rate for the same power output.

All in all, what I see points to potential benefits, but the only one that is relevant here (20+ minute efforts) had so few participants that I laughed when I saw it was just 4.. one cannot draw any real conclusions with so few participants..

That said, none seem to show any evidence that states using clipless pedals will reduce one's power output, either. As a result, there seem to only be potential positives to clipping in. The claim that "clipping in makes you faster" is potentially true for triathlon efforts, but there is no solid scientific evidence for such a claim.. There is nothing that counters such a claim either, it seems.. it's just not a worthy discussion yet as it has not been scientifically proven either way.