This is far more indicative of a problem with the cabal as a whole than DB being balanced because it makes ranking awesome.

A defender can do just fine without a berserker, so yes, they can heal. They also can have bards in the cabal. If the problem is no healing, the solution is simple: recruit bards and defenders. There is no law in CF about cabal leaders saying 'We're recruiting X classes. If you are not X class, it's time for you to #### off.'

Using non-cabal healers only very rarely factors into ranking and only depending on your group composition. It's more frequently abused by neutrals with bad RP (darsylon, darsylon, akan, darsylon) than it is an actually clever move (arkham crypts for goodies, who need an edge like that since the imms made it pointlessly more difficult).

If you want an actual tank in Village, stop recruiting people with no dex or tanking legacies or use more doubleblock. The mana is an issue but bards can do this neat trick where they turn off autoassist, get drunk as hell and rest instead of swinging their sword pointlessly when their weapon skills are 100%. People taking a scout are often going to be some version of: tank warrior, assassin, bard anyway.

In short: total red herring.

Bard Repertoire Clarifications:
http://forums.carrionfields.com/dc/dcboard.php?az=show_mesg&forum=6&topic_id=23735&mesg_id=23735&page=