if people want to spend their time in collecting those barrels and setting them up for a fight they know is coming, that's up to them.
it's cool that they have the choice in this game to do so.

I personally would not spend that much time in preparation but I will also not force another person to play the game in the way I feel it should be played.

So kudos to them for coming up with that idea...but not like i'm going to use this tactic should i come to the same encounter