Say what?
Professional reference monitors are OLED.
The Pro Display XDR launched as a cheaper alternative to OLED reference displays.
No, current state of the art professional reference monitors are dual stack LCD. Not that it matters as they're not productivity monitors anyway so it's irrelevant.
Aside from the text clarity issues that have plagued OLED up until very recently, with the introduction of stripe sub pixel layout that should be fixed, there is the huge problem of burn-in.