[lonelyasacloud]

Different domain, I know. But, fwiw, the best personalised content recommendation thing I've found that did a good job of both finding new related content _and_ busting siloes was the Last.fm music social network/streaming service.

Last.fm used you've got X in your library/listened to X, other's into X also liked Y algorithm to suggest and stream a mix of music you might like. It was sufficiently good that in 2012, they had to admit that 43 million of their accounts had been compromised when they were hacked. Their original business model eventually failed, and in 2014 they ended up removing streaming. And with that, it effectively became a music version of Good Reads. Which, although it is still going, killed it for most people.

Anyway, there's quite a bit of quality writing about Last.fm and its demise, e.g. https://www.washingtonpost.com/news/arts-and-entertainment/w... , https://www.vice.com/en/article/a37x9g/lastfm-was-the-only-m.... For my money, Last.fm must be about one of the best case studies into what works well and what does not. I would have a read if I were thinking about something similar.