Well I did raid quite a lot and I can say, it still sucks. Raiding is something you do with 10 people, everyone knowing their role.
This is for far more people including pugs on an open world map. Most raid builds are absolutely disgusting to play in open world while most open world builds are omega troll on raid bosses.
Example: Most open world builds are half DPS/ half survivability with a lot of people going toughness/vitality.
Which is basically a troll stat combo in raids. But how would you survive enemy after enemy after enemy in PvE without proper self peel? In Raids, you got designated healers for that after all.
So a Raid DPS with 0 self peel can quickly get burst down in PvE by some rando enemy. And an open world pug with half tank half dps build who doesn't know the mechanics at all will only scale it all up.
So how can this be solved? Pugs git gud, this even isn't as hard as it seems but probably just scaled up to the point the handful of good players can't solocarry.
Build switching. Get a raid build in reserve just for this fight. Works best with an organizing commander.
Organizing Commander with Ctrl V. A lot of Ctrl V. For the mechanics.
At the end, I assume it turns into tequatls difficulty wise. Everyone will know what to do when and it's super easy because the amount of afk people contributing nothing but scaling to the boss diminishes.