>couldn't such a service also employe a HackerNews style voting system - basically if a song started getting flagged by users as 'copyright violation', it would start to disappear down any searches or catalogues, until enough votes caused it to disappear from the service altogether?
depends what your users' interests are. if they genuinely want the site to only offer legal music, then sure it might work. but if most of your users are using the site as a free streaming service, it's not in their interest to remove music that they like.
Even youtube is suffering from blatant copyright violations with all those piracy live streams. I still don't completely understand why that suddenly became a thing.
depends what your users' interests are. if they genuinely want the site to only offer legal music, then sure it might work. but if most of your users are using the site as a free streaming service, it's not in their interest to remove music that they like.