Yes, people can benefit from more workspace.
But it depends a lot on the complexity of a task. And on what can be considered a 'screen'.
If you're writing text (after you've done your research and make a setup) then you don't need any other information. And many people specifically go to a clean/minimal environment to get rid of distractions and chaos. For example hemingway or good old notepad instead of MS Word.
But if you're still in the early research phase you often switch between sources, a list of them, and a document where you outline your article, then you can benefit from multiple perspectives. The same goes for other tasks like modeling/drawing from reference, or for previewing html or programming.
Then on to the second point; what is a monitor? Like nightning mentioned, it's not so much amount of screens as it is amount of pixels and workspace.
Way back when, people only had a 14 inch CRT and 640x480 pixels. Hardly enough to hold even one app, let alone reference. So when you needed more workspace, you needed more monitors. But nowadays everyone has a 24 inch full HD screen, which has over 60 times as many pixels. Of course some of those are spent on anti-aliasing and more detail, but it's obvious that current screens easily offer twice the workable space compared to a pre-2000 CRT¹.
And interfaces have improved too. Decades ago, in the age of DOS, software ran fullscreen and you could barely switch. Then, windowed interfaces appeared, followed by window-organizational tools, and currently windows has a pretty elegant split-screen function built in. And of course Alt-Tab still works.
Essentially, we now have multiple 'monitors' when we need them, and a single large monitor when we want to present or view something, or want to work more focused.
1 - yes, there were 21 inch 1600x1200 CRTs. But those were high end, and can be equated to a current 4K 30 inch monitor.