People go into dungeons with a full glass-cannon build and then complains when they get one-shotted. I find that hilarious.
Survival > Damage. It’s as simple as that. Don’t go full out on offensive stats, utility and traits. You need to bring a healthy mix of offense, defense and utility. Bringing useful boons and conditions that benefits your entire group instead of abilities that makes you do a bit more personal damage.
And then it’s a matter of learning the different abilities and animations of the enemies. You will get destroyed at first, but when you get more experience and learn the fights you will come out as a winner.
Me and two friends are clearing explorable mode with just the three of us, and we are doing it very successfully, for fun, laughs and the challange.