OLEDs have almost perfect Pixel Refresh Latency (< 1.5ms). MicroLEDs are still just LCDs with a better backlight but LCD Tech has evolved quite a lot and pixel refresh time (< 3-4ms) is not much of a problem anymore.
MicroLED is more akin to OLED where each pixel is self emitting. MicroLED is almost the holy grail of displays and will more than likely obsolete MiniLED.
You're thinking of MiniLED, which is just better LEDs behind an LCD.
MicroLED is a whole different ball game, with no LCD at all. It's just red, green, blue LEDs, one for each pixel.