Source: 99% of oleds cause terrible eye strain. Flicker affects people even when they don't realise it (studied for office workers during the CFL era iirc.)
But in general you're correct. When given a choice, I'll generally buy IPS when I can.
Apple and Google could do something about it if they wanted, even without changing supplier. They clearly don't think it's worth it. That's not surprising coming from Google but I admit I am surprised that Apple has no driver option to reduce flicker.
Most Chinese phone makers nowadays offer settings to reduce OLED flicker greatly, usually at the cost of color accuracy and/or a locked framerate.