Unfortunately, a metadata "database" is only as good as the data you feed it. This may be limited by how much effort the end user is willing to put in.
Adding metadata to an existing music collection can be a huge PITA. For anyone tempted by the idea of doing it for their collection, I thoroughly recommend taking a look at MusicBrainz Picard. It's a cross-platform application that can analyse your music albums and attempt to match them against entries in MusicBrainz's vast database, populating your MP3s / FLACs with appropriate ID3 tags and cover art when it finds a match. If you have a large collection, it will still take some time and effort to get right, but you'll end up with something beautifully organised afterwards.
I still keep all my music (~20,000 tunes) in a simple folder / file structure, but every album and song is tagged correctly, along with cover art, so that I can also feed it to Clementine, Kodi, DNLA servers, Google Music, etc. Best of both worlds.