I feel like it's probably more meta in large group fights, but a build with a very high capacity for boon strips and corrupts will completely shut down a healing/bunker guard, such as a curses/condi scourge. Firebrand relies on protection, aegis, stability, etc. as a buffer for the healing to actually be effective against burst, hence why they seem unkillable. The blocks, high damage reduction, and stability will cause one or more glass cannon players to use up most of their rotation and cooldowns enough so that a counter burst from your team can decisively win the team fight. Shutting down that buffer would easily be enough to burst through any amount of healing a FB can output. Coordinated heavy CC and high damage (literally baseline for any roaming dps classes) will absolutely devastate any team whose FB is being locked down with corrupts and strips, especially if the group is overly relying on the healing and boons to come through.