Well just reading the series description makes it sound ridiculous. When my guild goes raiding, if we had a tank that could act as infinite damage sponge, they would be taking the point every time. I run heals from time to time and I can imagine how ridiculously easy it would be when you basically don't need to pay attention to the tank at all. Barring special encounter mechanics that mandated alternative approaches, the team could just waltz through the raid.
(Said special mechanics including but not limited to: instadeath mechanics that work past HP, damage that applies as percentage of your max HP so no amount of HP is safe amount, narrative fail states that end the raid, routes that require splitting the party, waves of adds that exceed tank aggro skills' target limits, and multi-tanking requirements in a single fight ie Tank These Two Apart or Enter a Fail State. These all exist in MMOs.)