1900+ on Karagga is impressive, particularly in light of the fact that your main spec is tank. I've seen people get higher, but it's not common. As for Fabricatorů Everyone gets insane numbers on that fight due to the damage boost. Your DPS there is much more a function of the speed of your puzzle solvers and the strategy you're using.
You dont see 1900+ on karagga a lot because people who can hit that easily are not doing NiM KP... and if they are it is in a very relax setting where they are most likely watching the TV while playing (speaking for myself at least).