Every DPS spec in World of Warcraft is in competition with every other DPS spec. It doesn't matter if you're playing the pure DPS rogue or the hybrid DPS priest, you want to be at the top of the meters. For some players, being at the top of their raid's DPS chart is good enough. For others, they won't stop until they're at the top of World of Logs' rankings. World of Logs is like a world-wide Recount.
When the first few Dragonwraths were earned by casters, their stock on WoL saw a notable spike. The legendary staff's massive stats and spell-doubling effect were incredibly potent. Every caster with Dragonwrath saw their DPS skyrocket. When the first few Fangs of the Father were earned by rogues, it was largely anticlimactic. Heroic No'Kaled, which had already been obtainable for months, was a viable competitor to our legendary daggers. No legendary weapon has ever been pre-empted as quickly as our daggers were.