Great summaries. I also have a real affection for my last.fm discovery, and I think it had everything to do with "deep discovery" going deep into the related artists pages. It really shaped my relationship to music and my love of music discovery and I sometimes find I don't click with people whose idea of discovery is The Algorithm(TM).

I tried to import my music life into Google Music, uploading my lifetime of libraries there. When they wound that down I just lost trust in online services and now do it through Nextcloud, which honestly is pretty awesome imo. There's no algorithmic suggestion for better or worse, but none of the "who ordered that" style assumptions imposed on you by the system like those you outlined above.