If a tank loses aggro, whose fault is it?

[Shougun]

Did you check their gear? It's possible they were a mediocre/learning tank with the ilvl gap, most people won't experience it if they play with similar players or when the content is actually relevant but a special challenge happens at certain ilvl creep moments when a competent player wields it and it can be pretty exciting. Way harder to tank when you scrape the barrel of ilvl and your DD capped it 50ilvls ago than it is to hold hate on any other boss scenario.

So losing hate if you're not living for hate in every moment is really not that strange. Of course it'd be great to always get great tanks but that's not going to happen (like any role). While you did your best so still Tank's fault I guess deepening on the gear difference I wouldn't be shocked this happened, especially on paladin with meh group enmity control (dat flash).