I mean, your same argument could be made for TVs/monitors as well. LG, Samsung and AU Optronics make the vast majority of LCD panels. You could buy an LG or a Vizio with the same LG-fabbed panel. In fact, even Samsung TV has been known to use LG panels:
AU Optronics, InnoLux, Infovision, BOE optoelectronics, IVO, LG - these do laptop panels (also see panelook.com ). There is some competition in TN/IPS. But OLEDs or specialized panel situation may be different.
https://www.forbes.com/sites/johnarcher/2017/01/23/samsung-f...