LEDs and OLEDs work the same way, the only difference is their composition. Standard LEDs use metals, OLEDs use organic compounds (which, yes, are more sensitive to breakdown over time, but come with the advantage of being smaller, lighter, more flexible, etc).

And actually, it's that size and flexibility that makes an OLED panel possible. An LED display is actually just a color LCD display with a white LED backlight; you need OLED to have the individual pixels generate their own light. Burn-in on a non-organic LED display would be a completely different thing (and is possible but rare).

It's only marginally more detailed on the chemistry, but conventional semiconductors (inorganic) are roughly like metal. Silicon is literally a shiny, meltable element, although it's more brittle than a true metal. Like metal, unless they react with something like in rusting, they're probably going to stay the same kind of metal. There's exceptions if you really abuse a piece of metal, but a laymen probably hasn't thought much about tempering and differences in crystal structure

Organic semiconducters are organic compounds, like a dye. Just as a dye can bleach or change over time, they can chemically change with a lot less outside help. This makes them prone to not working the same way after prolonged use. Blue and violet are the most energetic colours, so it makes sense the components emitting it would break down first. UV OLEDs would be even worse.

The reason we don't use arrays of inorganic LEDs as screens (yet) is that they're really picking hard and exacting to grow. The standard way to do it is grow a wafer which is about screen size, and then cut it up into tiny sections, only some of which will work, and each of which is worth something significant on it's own. OLED can be grown in less crazy conditions, more like just printing with ink, and Micro LED gets around the wafer problem by using a precise robot arm to handle, test and connect each sub-pixel individually.

Just to tack on and expand on your first point: LED monitors are normally LCD displays but with LED backligthing, allowing for more zone control and it is more efficient both with space and energy usage.

For TV’s, burn in is becomming less of an issue due to software in newer models and improvements in the tech. The same goes for phones. Older OLED phones like the Pixel 2 I think, had issues with burn-in.

Rtings is actually doing a long term torture test as we write. They have also included some PC monitors for good meassure.

In general, the reason why it’s still not perfect for PC is that all office/daily use retains a static image on a large portion on your screen. Imagine a browser, Excel or program with a big static toolbar. This will cause issues even with pixel shift and refresh cycles. You can only move pixels so much without it affecting your experience.

If you were to only game or watch movies on it, it would likely never show signs of burn-in.

Hope this made sense

Yes, but our phones are OLED and most TVs sold are plain old LED.