Quote from GT4
Besides the OP having ridiculous gear, here's something to consider:
Diablo is actually one of the bosses with the lowest auto attack DPS in the game. Most DHs don't know this but if you ever did Diablo on a melee character, you'd know his DPS (and moreso his damage per swing) is actually lower than that of quite a few trash mobs, even non-elite ones. It was obvious you'd eventually replace SS with SP once you have the defensive stats, but it's still not permanent while farming and more importantly, it doesn't allow you to tank high damage enemies and especially not affixes either.
A small comparison:
Using my Monk and a full tank build (even though I'm not usually doing Diablo with a full tank build - since he hits like a wet noodle I usually do him with a full DPS DW build), he hits me for roughly ~8-12k in P1. There's quite a few trash mobs in Act 3/4, especially when rare or champion, that can straight-out one-shot me (with ~36k HP) using the same build.
After the patch, it may also work out well for champion/rare packs. However it also needs to unless you want to farm ridiculous repair costs.
Diablo's DPS is fairly low this is true. He does hit somewhat hard though. There are certainly mobs that hit harder than he does, like the pony's who hit for about 2x his damage. I can still tank those with gloom up. My gear has also gotten a lot better since that video. With my cooldowns popped I can usually tank longer than my monk friend, who is full tank specced at 63k hp, 2k+ hph, can't recall resistance or armor, but he can usually tank everything in the game without taking any damage with the exception of beams/firechains/fire. Obviously you cannot tank everything.
You are also very correct about the next patch. Mobs are going to hit for less, but still 1 shot glass cannons. Glass cannons can no longer have Tyriel kill stuff they can't kill. I guarantee you my repair costs are much lower than glass cannons as well.
Also sorry for not responding to questions, I thought this thread died :(.