Minimize is one of several ways of coping with desktop clutter. I tend to have a lot of open apps, often with multiple windows in many of those apps. Basically, the size of the available desktop helps determine whether I can leave those windows open or whether I minimize some of them to declutter. Sure, I could just allow them to get buried in the stack and click the Dock icon to bring them back to the top, but the act of "putting away" a window or app helps me to stay a bit more organized - do I click around to find the (buried) open window, or do I move to the dock to reopen it?
I've dabbled with multiple workspaces over the years - let's say a major project on one workspace while my day-to-day stuff resided on another workspace. But outside of project-switching I've found arranging multiple workspaces to be more trouble than its worth - there's inevitably one app/window that I need that ends up on a different workspace. By the time I find it, I may as well have been working in a single workspace and minimizing when a bit of declutter is helpful.
I used minimize most when I used laptops (that was before the days of Retina resolution) - smaller workspaces get cluttered quickly. With so many windows stacked/overlapping the "pile" could get pretty deep - minimizing reduced the depth of the stack.
On my 20" iMac (which meant it wasn't a Retina) things were better, but still not as much desktop space as I wanted. A 27" iMac gave me more room to spread out = less minimizing. Better still is the dual display setup on my 27" 5K Retina iMac plus a 27" LG 5K external display. Still, even with all the desktop afforded by those big, dual displays there are still a few apps that I minimize.
Mostly I minimize infrequently-needed apps - I always run Activity Monitor, but I only need to view it when I run into system slow-downs, etc. I refer to Calendar and Contacts infrequently, but still prefer to have them running. And when I have a lot of documents and spreadsheets open I tend to minimize the windows that are not in active use - it helps keep me from accidentally typing on the wrong document.
But we each find the workflow and methods that work best for ourselves. If minimize isn't helpful to you I'm not going to try to change your mind.