I tried doing dungeons with Minion Master build and they were just aggroing everything. It was so much more inefficient than Condition build with one or two minion skills for meat shields. I don’t know what kind of party you’re running with but just because people are level 80 doesn’t automatically mean they know what they’re doing.
I think you just encountered one of the nasty elitists. I just did my first dungeon run last night with a couple of parties and they were all very forgiving with one or two exceptions, like when people just charge in and aggro the whole mob, but that understandably pisses people off especially when you’ve been explicitly told to wait.
He won’t be the only person who’s been through the dungeon so you’ll have no problems finding someone else to guide you. Some people are just really obsessed with their token count.