2048x1536 displays were available on laptops a decade ago[0], and they were IPS. That's a megapixel more than 1920x1080.
I'm sure the inability of Windows to cope with the high resolution gracefully was part of the reason those never really caught on, but there wasn't much of an effort to market them either. Did you know they existed? I barely did, and I pay a great deal of attention to such things. There was no meaningful effort to market them. They were custom-order options that only a few enthusiasts and institutional IT departments would even be aware existed.
My mother knows what a "retina display" is.
[0] If you're curious, the models offering QXGA panels were the NEC Versa P700 and the IBM/Lenovo Thinkpad R50p. Such panels can be made to work with several other 15" 4:3 Thinkpad models.
