Ya'll know that it is possible for something to be more powerful and less efficient at the same time, right? What are you all arguing? Power or efficiency? It is quite possible that "pulling up" benefits only one of these two metrics.

It is clear to me as a long time cyclist and racer that clipless (or any other solid foot retention, such as clips and straps or the duct tape you see on "breaking away") increases the amount of power you can put to the wheel. Does it increase efficiency? That is less clear. But sometimes you just need power.

Case in point: one time before a cyclocross race, I was riding around the venue with regular shoes (no clipless or straps). I went down a short, relatively steep driveway entrance to talk to someone; turning around to come back up, I had to almost walk the bike because I couldn't generate enough torque without lifting the recovering foot to get me up that hill in the gear I was in. With clipless I would just power up. Without I was limited to standing essentially one legged on the drivetrain to make it move.

Now then, picture a steady state, flat time trial; would I need clipless or straps? Probably not, if there is minimal acceleration required. The only advantage of foot retention in that case are the secondary effects of keeping your foot placement consistent and bike control. This is why, before clipless, road riders would ride with their straps relatively loose unless they had to climb, accelerate, or sprint. It used to be an indicator of someone about ready to launch a breakaway that he or she would tighten their straps prior to the effort.