Link Jeez a lot of questions. Let me try to answer some:
Plasma "pwm" is not an issue because the phosphor persistence time on plasmas is so long that any modulation of the signal is incredibly mitigated if not impossible to see/measure. In fact, it's such a long persistence that there's an afterimage when you turn the panel off that lasts for a few seconds... On an LED it's starkly visible because the persistence on the light is very short.
Plasma "dithering" is a subfield dithering, it's VERY large and stark. It's disconcerting if you sit close, if you are further away you don't notice it. But it's literally an ordered pixel dance that cycles different colors through areas of constant color to provide shading/depth, sort of similar to old tube TV's, and definitely can be distracting if you don't like it. I don't mind it, and it helps color depth substantially. The "temporal dithering" on other units is done at the actual pixel level. A solid purple screen on a Plasma is ... purple. Maybe it's mostly purple with a bunch of green sort of floating through it because you asked for a deeper purple. A solid purple screen with temporal dithering is... every single pixel flickering back and forth from red to blue in unison (or a pattern) to simulate purple, and literally hurts to look at.
We know the XBox and PS4 dither because ... well, you can SEE it if you get close to the screen. It's actually visible. Temporal dithering looks like a shimmer where the color swims and won't sit still. You can easily see it on large screens. On small screens it can be tough because of pixel density.
The Switch might dither, to be honest. nVidia is nowhere near as safe as they used to be. Last-gen Tegra chipsets had ZERO temporal dithering. New ones might. I haven't tried it. The built-in screen has good and bad versions, I've played with a few, but I've never plugged one into my plasma to see how it looks when piped over HDMI.
And yes, of COURSE if a device specifies dithering the monitor will do it, because it doesn't say "hey, dither that image!", it presents a shifting series of pixels. The TV can't tell if that's a moving image or a still image with dithering!
Listen, a true 8-bit PWM-free LED... and that's super rare and super expensive, because DC direct current dimming requires a LOT more electronics so it's usually a LIE... would be nice, assuming the color output wasn't also painful. A lot of people here are sensitive to blue light in addition to the PWM. But the reality is that if the source is dithered - and all ATI chipsets are dithered regardless of whether the output device has 8 bit color or not - it won't help.
Temporal dithering was designed to solve a problem. The problem was (and still is) that most displays have a CRAP color gamut. They're mass-market produced, and designed to make colors "pop" so that the average consumer thinks they have a great display and buys it. Most output devices ASSUME that the display they are attached to can't render the colors they output properly... and dither just to make sure.