What I mean is that it's possible to have, say, Debussy playing without having to actually pay attention. Not so with Bach.
It depends on what you're listening for and what you think is worth paying attention to. If it's counterpoint, fugal writing, etc., then sure, Debussy has less to offer than Bach and can safely be relegated to the background. If it's the extension of diatonic harmony and/or the use of non-functional harmony, I'd say it's impossible not
to pay attention to Debussy's music when it's playing, and by that particular standard Bach can serve as sonic wallpaper as easily as Telemann, Corelli, or any other Baroque composer whose music is most often found in dentist's offices today.