Tanks aren't rare. There's too many of us for the amount of endgame offered. <_< All of you should go switch to heals/DPS so I can be the last of our kind o/

In all seriousness, I believe in the leveling game, there is a clear lack of tanks. 1-50 there's really not enough tank/heals to go around, though this might be due moreso to the ratio of tanks:healers that are leveling...

However, in end game, it tends to be much easier to find good tanks. So I think the "Myth" as you said ends at 50.