https://www.dell.com/en-us/shop/dell-laptops/dell-15-laptop/...
It is very, very common. Just not in the Mac world.
1920 x 1080 51.89%
2560 x 1440 21.20%
3840 x 2160 5.00%
To me, it's more about what I'm used to. I have a perfectly fine several years-old monitor, so why should I throw it away?
Other way around, most Mac software is not tested how it behaves on inferior external monitors.
Edit: Guess it depends on the app
Whether good letter shapes is more legible or crisper text is more legible is basically subjective. In the 2000s before HiDPI became popular different people really thought one was more legible than the other and vice versa. HiDPI made this basically moot.
If you work with text and fine UI elements, do yourself a favour and get proper tools for the job. Get an ergonomic mouse and a good keyboard while you're at it. In every other field professionals use high quality tools to do their jobs, IT shouldn't be any different.
A plumber has equipment worth tens of thousands of dollars, while IT professionals think it's outrageous to pay a few hundred for equipment which is undeniably an improvement.