Hi George,
one thing to remember about the MusicBrainz database is that its content is predominantly uploaded by public users so when you have a CD that has only recently gone on sale
or has a low ownership then your chances of the information being in the database and the completeness of that information are greatly reduced.
This is going to be true of every public database.
The information about a particular CD includes the DiscID which often gets added when a given CD is ripped by particular software that can upload the information to the database.
The design of the B2 is such that it can be used as a "one box" solution (which suits many) but also has the ability to work with more sophisticated tools.
That means that the B2 ripping software is relatively simple to use and is not currently user configurable other than the CD title selection when there are multiple matches.
dBpoweramp is much more functional and configurable ripper that has lots of bells and whistles including the ability to search multiple sources for CD information.
Even it can be found out though and I have on several occasions had to use its manual search to get info from Discogs.
I always rip on my PC because it gives more control of the rip, particularly naming, and automatically gives me a backup copy of what I upload to my B2.
John