Altho ESO has some sort of trinity, it works in a diffrent way then other mmorpgs. For example, you can have a 12 man group with 4 semi tanks and a mix of semi dps and semi heal and all have more then 1 role in a group or if you want, focus more on tanking, healing or dps. A group is much more involved in a fight. That is my expirience and they have done a good job if you ask me.