Well, the current last.fm "play your recommendations" is linked to spotify, so maybe you're right? Last.fm has gone through phases of no streaming, streaming, and partner streaming, and TBH I haven't used last.fm as a stream source in quite a while. I guess it seems possible that if they outsource their recommendation playback to spotify, you'll get spotify recommendations.
Outside of the spotify integration, last.fm doesn't have visibility into anything that isn't scrobbled AFAIK. It's based on user data only. You have "neighbors" who have similar tastes, which I think is calculated based on overlapping scrobbles (not sure if time-weighted, or just top listens). If we both start scrobbling with a limited amount of artists, and 75% of our scrobbles are the band Primus, we're probably going to be neighbors. If I decide that Primus sucks and start listening to Coldplay all day, our venn diagram overlap separates and we're not neighbors anymore.
Maybe the neighbors influence the recommendations, but playback is outsourced to spotify? I guess I don't really know. You can still browse neighbors though, and use their top lists as "recommendations", which should only be based on listening history.
Outside of the spotify integration, last.fm doesn't have visibility into anything that isn't scrobbled AFAIK. It's based on user data only. You have "neighbors" who have similar tastes, which I think is calculated based on overlapping scrobbles (not sure if time-weighted, or just top listens). If we both start scrobbling with a limited amount of artists, and 75% of our scrobbles are the band Primus, we're probably going to be neighbors. If I decide that Primus sucks and start listening to Coldplay all day, our venn diagram overlap separates and we're not neighbors anymore.
Maybe the neighbors influence the recommendations, but playback is outsourced to spotify? I guess I don't really know. You can still browse neighbors though, and use their top lists as "recommendations", which should only be based on listening history.