This isn't completely true, only for white "lamp" leds. A monitor or tv or phone generates white light from coloured LEDs in a different way, mixing up the direct light from the LEDs. The reason that matters in this dialog is that unlike the light from white lamp LEDs, the light direct from each coloured LED is coherent, single frequency like a laser, very low interference between one another of the photons comprising the output light beam, thus concentrated, not dispersed. In theory, turn the power up enough, and it will laser the eyes.
It might not seem to matter looking at one or two pixels in a screen, but scale that up to HD, or even more, 4K, 8K, whilst the LED efficiencies are still getting higher and higher, and it surely starts to matter, especially for the very common scenario of white background scenes.
Add to that many monitors now are curved, with the intention that the user sits in the focal point of the curve, like receiver in a microwave dish, it keeps getting better :)
It worries me a little anyway, I have such a monitor, and have to use it a lot.
I suspect OLEDs are far healthier.