The Spotify website and phone apps don't just have performance issues, they have awful bugs that have been left unfixed for months/years. When streaming to a Chromecast, the UI quickly gets out of sync, randomly disconnects, etc. I'm resorting to using a bluetooth receiver connected to my amplifier because that works better. The recommendations are also getting worse IMO, though that's more subjective, hard to quantify, but the amount of time I spend using Spotify has gone down a lot, just because I'm not discovering enough interesting tracks anymore.

IMO, Spotify is neglecting its core features, and that will ultimately hurt the platform. However, there is such a thing as network effect, and they may have the broadest selection of music. That will keep the platform growing, up to a point. Eventually, the growth numbers may peak and slow down. It's just that there's a lot of inertia right now, and the growth is still going upwards, but eventually, gravity might catch up.