But the OP's point was that using workspaces in a tiling window manager removes the need for so much physical real estate. If you have a very fluent i3-based workflow, the limiting factor becomes your own human capacity to focus attention, at which point a single decently large monitor (that can hold, say, 4 windows comfortably per workspace) is all you'd ever need.
3 monitors is just a workaround for a workflow problem that i3 can solve.
> I do the same and have triple displays that is placed with ergonomics in mind,
meaning that the author uses both i3 and triple monitors.
I use a laptop and two 27" externals, not with i3 but with an auto-positioning Hammerspoon that has a similar effect.
When I'm on smaller or fewer displays I can't fit everything I want up simultaneously.
Granted, I relatively often have a mobile app codebase, a backend API codebase used by the mobile app, terminal sessions pertaining to each of those codebases, and documentation for the tools used in either or both projects up all at once.
My eyesight isn't great, so all of those have fairly large font sizes.
Not every project needs that much context. When I'm hacking on my Emacs config, a two-pane split is about I can ask for (and one will do the job just fine).