Well, not everyone is able to survive Perillious without barrier. So yeah, for "low promoted chars" that's the best way.
Even with few promotions, with a full barrier bard, you can easily clean FC in Perillious.
My stats are 23/17/17, I do not have the best gear by a long shot, and only just recently started playing with HoK. Somehow, up till now I've not had a lot of problem surviving in Perilous unless I had a really under leveled character without so much as a hint of Barrier. I am not some super-elite player with hundreds of promotions like (no offense, guys) Drasca or SpaceV3gan. I just play smart.
Yeah, I may not get top score when playing with guys that have tons of promotions, but I don't really care about that.
Furthermore, Zither! is honestly not good as a Barrier class. You are really missing out on a ton of awesome fun with various builds he has by focusing on literally the first song he gets. He also is not as good as on par with a solid Elementalist or Keeper build when it comes to Barrier.
Again, it's a complete waste.