Interesting take. I regularly switch between just the laptop and my 3 monitor setup. Sometimes I feel like I could use a 4th one because there is just so much stuff to look at when developing. When I get to my laptop I sometimes feel like I can't be really productive on it. Having to tab all the time is not in itself an issue, but I keep getting lost when I have multiple instances of an app open - e.g. IDE. Say you have 3 projects open, I feel like I keep tabbing to the wrong one all the time.
But overall, I do like the idea that you don't actually have to see everything at once. Also takes focus away I guess. I would love to see a study on this which tries to actually measure this.
Single-screen user here. I like virtual desktops in addition to alt-tabbing.
I feel that tabbing to the wrong instance of an app is a problem that can be solved on the software level. It’s a nightmare on the default macOS app switcher. I use an app called Contexts as a solution and it works reasonably well. There seems to be some free and open source solutions as well.