Like the Subject says, it's not possible to permanently prevent the Web Helper from starting with Windows, and after literally years of requests from users, it's very clear that Spotify doesn't care. So I simply uninstalled the Spotify application for the Windows desktop.
Don't get me wrong, I love Spotify. But I've got other ways to use Spotify so I won't miss the desktop application. Not trying to make a statement here, just saying that I don't let arrogant software developers get under my skin.
Solved! Go to Solution.