[Reason077]

I don't really want widgets cluttering my desktop, I want them in their own space (ie: their own desktop).

The use case for me for widgets is to display information I want to look at very briefly and then have go away again.

It ought to be pretty simple for Apple to add a "special" desktop for widgets to the left of the first desktop. This would match both the old Dashboard behaviour that I miss, and the way that widgets work on iOS.

(And the gesture you describe isn't "show desktop", it's "show all windows", though I'm sure it can be configured in macOS settings!)