The crux of Spotify was the acquisition of Echo Nest back in 2014: https://www.theguardian.com/technology/2014/mar/06/spotify-e... I tend to think whatever good bits we see (Discovery being good) is sitting on the shoulders of that base work. Yet, the product values of Spotify do not align with these people or musicians anymore.
I'm not so sure they deserve all credit for Spotify's discovery features - those where at their best right after Sander Dieleman and Aäron van den Oord were interns there, and both those guys were snapped up by Deepmind and have a ridiculously good publication history by now.
But that Spotify is going to get a ton worse without MacDonald, is pretty certain.