Most of DF groups need 15-20% echo just to be able to kill garuda, because it is a dps check battle. If team disbands before that - they have not even tried to kill garuda but wasted time instead.
People did garuda before the echo, but with 1 healer. In DF there are 2 healers, so they must either both dps (very unlikely) or you need 20% echo to compensate this.
Other than that there are 3 ways team can fail.
1. Someone killed the spiny - mark the spiny 'target to ignore', it helps a lot with people who speak a different language.
2. Tanks forgot to provoke the spiny when 2 stacks are reached - create a macro with a sound signal so one of tanks will provoke when it is required.
3. DPS not knowing what to attack - mark garuda 'target to ignore' and adds by 1 and 2.
I killed garuda more times through DF rather than PF. Garuda is one of the very few endgame dungeons that are not a ping check, i hope there would be more dungeons like this. Next dungeons are a heavy ping check though.