Blade and Soul has an interesting approach to group mechanics. As I understand, it's not quite Trinity gameplay, but it's not quite a zerg either.
Threat exists in BnS. Blademasters and Kung Fu Masters are considered "tanks" and have higher threat output. Their damage is still roughly the same as the other classes. Threat also appears to decay fairly rapidly, which means the tanks have to keep up with consistent threat output. But DPS can stop doing damage and will drop threat reasonably fast, and then not pull threat immediately when they restart.
However, there are no healers in BnS. That part of the trinity is entirely missing. The tanks rely on active mitigation, blocks and counters, and some self-healing to keep themselves alive. The other classes also rely on their defensives, mobility and potions. There are some group defensive abilities. I believe Summoners can occasionally heal the group, and Force Masters can put up a defensive shell that protects people under it for a few seconds.
The end result is a quasi-zerg, where everyone is attacking the boss with their full potential. But it's a controlled zerg, as the boss is generally attacking the tank, rather than bouncing from person to person. This means that incoming damage is very controllable, and if you play well, you can do an entire boss fight with minimal loss of health.
It's reasonably fun, because you do function as a group, and the quality of your play matters. As well, no one is forced to play a low damage characters. The tank classes generally have blocking and countering being central to their damage combos, so they want the boss to attack them. However, they don't have a taunt, and they don't really "control' the fight the same way a trinity tank does.
This structure is better than straight zerg or kiting. However, I don't think it's quite as good as Trinity gameplay. In particular, I don't think it can provide the variety of encounters that the Trinity structure can.