It allows for data analysis. This helps you to discover new music, keep track of new releases coming out. It also allows you to easily share your musical interests with others. And it doesn’t have blind spots. Spotify would never recommend you something that’s not on Spotify. Because people submit listens to ListenBrainz from Spotify but also from other platforms and from local files there are no inherent blind spots. My listening behavior is no secret, anyone can have a look at it, I choose for it to not be private. But I wouldn’t want to just gift it to any one particular ompany that can use it to make money. By submitting listens to ListenBrainz you basically gift it to everyone.