[x] Works on relatively low tech hardware
[x] Doesn't require internet connection
[x] Can't be removed from your possession for violating ToS
[x] Can be easily backed up
All of the above is true for Bandcamp except needing an internet connection initially but I don't imagine that's such a limiting factor. There's still CD sales going on there so the above doesn't explain it completely and I imagine the nostalgia, having a physical item, contrarianism etc. have a bigger hand in the resurgence.
