Look Nord DK tank was very very common combination for 5 years. I bet the significant majority who plays since 2014 has a Nord or Imperial DK Tank.
Well, of course, because if you wanted to be a tank, a Nord, Imperial or Orc DK were the best options. But, even back then the numbers of tanks were completely dwarfed by the number of DPS characters, more often than not the Tank position in groups were filled by Templars. Tanks were hard to find when grouping. That was back in 2014/2015, and it seems that it hasn't changed. Everything that I have read before coming back to the game says that Tanks are very hard to find. No waiting time if you are Tank, small waiting time if you are healer, long waiting time if you are DPS.
But, I didn't pick the Nord DK for rarity or anything like that. I picked it because I have 4 other ALTs from before and DK was the one that I hadn't tried. So it was a chance to start the game with something completely different for me.