Here's my understanding:
Situation 1:
Team has a good builder, and a crap builder who keeps ruining the base.
With the DB system, the team would vote for the former to be a DB.
The DB can then protect everything, and block out the crap one.
Situation 2:
Team has a good builder, and a learner builder who listens to instructions, but still makes mistakes occasionally.
With the DB system, the team would vote for the former to be a DB. (And the latter would agree)
The newbie can then help out, without people worrying about him deconning something important.
Situation 3:
Team has a few good builders.
With the DB system, there would be no problems and a DB would never be voted in.
The game continues normally.
I think the second is not something people have considered yet either.
(Probably because there are many n00bs, and few newbies willing to learn)