The whole point of Last.fm is that you get stats on your listening habits (and those of your friends). The realtime thing is just how the system collects the stats. Besides, even there, my friends' "Now playing" stuff in never bigger than a small icon on the side. It's not the core of the site.
Facebook, with Spotify, gives you the useless part (the "Now playing") without the good part (the advanced stats, recommandations, music compatibility, etc)
Facebook, with Spotify, gives you the useless part (the "Now playing") without the good part (the advanced stats, recommandations, music compatibility, etc)