When I linked my pre-existing spotify account to facebook a week or two ago, I was explicitly offered the option to disable that feature as part of the account

When I linked my pre-existing spotify account to facebook a week or two ago, I was explicitly offered the option to disable that feature as part of the account linking wizard. And obviously you can disable it in the preferences. It's a big oversight that they didn't give you the same prompt as part of that otherwise very slick story you described.