It's not a health hazard, but it is a bottleneck in a very real sense if you want to keep more than one thing open (whether for reading, writing, running commands, or a combination thereof). It's not just a matter of preference.

I use a tiled window manager + emacs buffers, my 15.6" screen almost always has 2 applications open and 4 when I feel the need. Never had a problem running commands or reading documentation all at the same time.

OK, it's great that this works for you. Some people can't readily adjust to tiling window management, and barely anyone will switch to emacs (for reasons that would take a couple of paragraphs to summarise adequately).

Even I use a tiling terminal application, but that still leaves me needing another display for the web browser and work chat, for instance.

> Some people can't readily adjust to tiling window management, and barely anyone will switch to emacs

Then those are preferences, not need. I agree a second monitor should be provided if asked, but in no way is it a requirement. I'm not alone in my preferences either. I learned to code in Turbo C where the line length was _puny_ compared to even this comment box here. I was probably more productive back then.