I've been thinking about this a bit and think I have an example that might help.

Think of clipless pedals like good track shoes (this is comparing to platform pedals). If all you plan to do is walk then good track shoes are pretty worthless. But if you plan on running then the track shoes pay off. They give you the best traction as you run. They let you perform to your full potential.

But those shoes are not 'shoes of Mercury' out of some video game that do the work for you. You still have to do the work.

I think it is the same for bikes and clipless. They let you perform, but they do not do the work for you. The one difference is that on a bike the line is not as clear as it is between walking and running. Even if you do not work hard that often clipless can still pay off. I do work a fair amount of the time, but I also get results when not working when a light is about to change and find I can accelerate much more easily, making a light I would have otherwise missed.

On a side issue. There are some things that almost do the work for you, or at least cut back a lot on extra work. Street tires for street use comes to mind.