We once went there with five sci on sci ships and had no problem in completing the optional, even in CSE. So, your argument is invalid. Of course its very easy with an all Tac all escort team, but it is easy with an all sci team too.
Of course that only applies for players who know what to do.
Ah well and dont confuse backbone with ships built to attack. Those are two different things. Escorts are built for battle. Cruiser are for exploration and diplomacy. For large transports. For evacuation. All things escorts suck at.
Was this a pre-made or pug? The system is supposed to work for any group that joins - as long as they follow the script then they should be able to complete the optional. But this is just not the case. I am not 100% positive but I think they removed a lot of the one shots but made the Borg NPC's a little tougher just recently.