I agree that the current setup is a little counter-intuitive. Workspaces make more sense as a master grouping of both Windows and Tabs. So when you flip to a new workspace, it would replace all of your open windows and tabs with new ones, truly shuffling you to a new task or part of your day, and freeing up those system resources.
For example, you might be working with stocks in the morning, and have 300 tabs open across a bunch of windows. Lots of graphs, lots of pages with company info. Then after market closes, you might flip to some research and articles, and have 50 tabs open across a couple windows. Then in the evening you might flip to an entertainment workspace, which has your favourite fanfics, YouTube channels and web comics open, plus some DnD research - only 100-150 tabs there across a bunch of windows. And finally when you need to, flip to your shopping workspace for your next computer upgrade or some Amazon.ca purchases, which might also have 50-150 tabs open. (Since wishlists suck and randomly empty themselves at many eStores. Amazon excluded.)
I would also use it for the occasional work project, like maintaining some websites for businesses. Right now I use tab folders that can open 10-20 pages, but I am annoyed by that as when I make new folders the old ones are always moved around. I'm used to Firefox/PaleMoon where they get added to the end, not rearranging stuff as you add more. The window for adding them is also so tiny, I can never see their names (should be 3-4x as wide and as tall as possible) - and it lacks F2 renaming, and doesn't keep folders open to subfolders, so organization-on-the-fly is hard - I would definitely use a workspace for this given the current state of the bookmark system.
And then some programming projects that I work on sporadically (maybe every 3-6 months), so don't need the tabs open. But when working on them, I need tons of reference pages up in front of me, so again I'd have 50-100 tabs. Once again, once you add that many as bookmarks, they get rearranged and shove each other around, and also clutter up your search bar when you type stuff in. Opera was not designed with having 4k-20k bookmarks in mind. True workspaces are just a better fit for many of these tasks.
