Admittedly, the Music Brainz database is not terribly comprehensive. The advatage that some computer ripping programs have is that they use multiple databases, so they have a much better chance of finding the right album info.
Yesterday, I was about to rip a rather obscure CD. dBpoweramp first came up with a Billie Holliday album - not even close. But I could select which database to try again. When I selected Discogs, it failed again. But when I selected FreeDB, it found it. Another reason why I rip on the computer.
And I cannot tell you how may typos I've found in the databases. Misspellings aren't the worst of it. It's not all that unusual to find two tracks with the same name and then a track left out and the succeeding track names off by one. It's easy to fix on the computer before you even rip. And then when you do rip, both the filename and the tag info are correct and you don't need to make double edits for each track.
That last example is something that would make a real mess on the B2. Good luck figuring out what happened.