I have never seen bad text rendering on an OLED. Which ones have you seen that have bad text rendering? I recently replaced a Sony X900E with a LG C4. Text is crisp and power usage dropped going to the OLED.

Permanent burn-in will happen with static images, but it happened on CRTs too and those once dominated the world. As long as it is infrequent, it is probably not much of an issue. Newer OLEDs, such as Apple’s tandem OLEDs, minimize the issue.

I am not sure what you think your point about black levels contributes to the discussion. Higher black levels would only favor OLEDs thanks to their inky blacks.

OLED displays don't inherently have poor text rendering, but they tend to use more exotic subpixel layouts than LCD displays [0]. It's possible to render text well with alternative subpixel layouts (for example, every iPhone), but if you use the standard RGB/BGR algorithm with PenTile displays, you're going to get bad results (but with a high enough resolution, it doesn't really make much of a difference).

[0]: https://en.wikipedia.org/wiki/PenTile_matrix_family

I mean you can just google this. It's common knowledge, I'm not dropping some hot new research here.