Except it's not just that, is it? They have more than one product. They have the desktop app, the web app, iOS app, Android app, apps for smart TVs, apps for smart speakers, internal admin apps, apps for artists, apps for venues, apps for labels.
Even if you narrow down to focusing on just one of those like the desktop app. There are so many sub-features. Playlist management, playback management, search, audiobooks, podcasts, merch, event ticketing, groups, collaborative playlists, local files, upsells from free to paid, notifications. I could go on.
It's a media player with a CDN. They should have at most 100 engineers.