After nearly two decades on a Mac, I've finally come to the conclusion that the Desktop is actively harmful. It is the junk drawer of the Mac. It distracts me, it collects stuff, things get lost there, I'm done with it.
Make sure nothing is being automatically saved to the desktop. The most likely culprit is Screenshot.app.
You can't actually delete the Desktop folder itself, because Finder will just recreate it upon finding it missing. You can instead render it useless by symlinking it back to your home directory1.
As an aside, if you want to keep your Desktop but want to put it somewhere else (like within Dropbox), these same symlinking steps will achieve this, just change the linked location.