I wholeheartedly disagree with the other comments.
These are gaming laptops, and having the FHD screen option allows you to play games at their native resolution without downscaling to 1080p on a QHD screen, which doesn't look great on a big screen monitor, even worse on a small screen laptop. In addition, for reading text, font rendering in general on Windows 10 is not much better on higher resolution beyond 1440p due to ClearType being problematic.
4K UHD is still very expensive for the vast majority and costs a lot of power to drive 4x as many pixels as a QHD display. Until we develop a technology to be able to get solid 12hrs of work-day battery on a 4K display on a laptop at less than 1 watt power consumption, Low-Power 1080p IPS displays will always be around.
Not to mention lowering the base cost of already overblown laptop prices
What matters more is portable screens moving onto HDR1000 and 10-bit color support, thanks to the introduction of longer-life OLED and the new miniLED technology with lower power consumption.