Gray Steam store userstyle/skin - with optional feature (e.g. curators) hiding

Unfortunately yes. To be able to change the style in the client, you'd need to inject JavaScript into the client's browser and load the css through it.

The daily deal column is in a different <div> parent element so just hiding the recommended for you column doesn't do anything. However, I moved it "manually" with margins and you can now install a version of the style that replaces the recommended for you column with the daily deal column. A JavaScript swap would have been more suitable.

No whining in this thread. That site is pretty pointless anyway because you should find a curator, whose recommendations match your individual taste, and not some popular one, whose taste in games might be entirely different from yours.