True for writing or any one-mode tasks.

For dev work though, typically I need see multiple things simultaneously: input (IDE/editor), output (console/browser) and instrumentation (debugger etc.)

I'm one-monitoring these days (WFH) because my laptop can't output to more than 1 display without a docking station -- I had left mine at the office. The context switching is tiring to say the least. I'm making do by tiling my windows but with a 24" display, there's just not enough room.

I think the author's setup works because he's using a 31" monitor and a tiling window manager. Most window managers don't tile as nicely.

That said, there are tools like Terminator and tmux, which are always useful.