+1.

I was thinking the same thing, and never heard of clipless being somehow better for knees. I ride clipless, so I don't think they're worse either if adjusted correctly.

Knee pain has to be diagnosed properly (sadly many "specialists" go with their pet theories over taking the time yo find your specific problem) to eliminate any serious organic issues. Then you have to address the root cause if cycling is involved. In most cases it's the result of riding too high a gear, or bad saddle position. If you use cleats of any kind cleat alignment is critical, or pedals need float or both.

Also, many less experienced cyclists do what I call bicycle isometrics. They push the pedals rather than turning them. By that I mean that the pedal can only turn in a circle, so high downward pressure before and after the 3 o'clock position means higher stresses on everything (including you). The pedals also want to turn at constant speed, and there's a tendency to try to move them faster by pressing harder.

By analogy, imagine you're trying to push a car. You can hurl yourself at it, or shove it hard with your arms, but all that happens is you get tired and the car stays put. However if you firmly apply steady pressure it's get rolling, and you can work yourself up to a run as it slow accelerates.

So it's the same with a bike, don't push the pedals down through the ground. Instead press them firmly for as much of the pedal stroke as you can, and even try to press at a forward and backward angle as you follow them around. The angle shift is hard to master, and most people save it for hill climbing at lower rpms, but eventually it becomes ingrained motion. Just concentrate on pressing only enough to make the bike go, and if that takes too much force, change to a lower gear.