Right, but my point is in order to make the plate set viable you still need to invest a hell of alot more than just starting off with a cloth set. Its throwing away money for no reason when you can use that same money to build up your physical defenses for half the cost.Celestial cloth will give more mpen, crit, and the full cloth bonus reduces debuff durations by 30%. I agree cloth is generally safer for raids. I disagree that reaching soft cap for defense is easy, as you will need +2000 defense over cap just to deal with puncture. However, puncture isn't a big threat in large scale PvP which is the topic of this thread. I'm just discussing that in many scenarios going plate can still be viable but a mage should aim for a good cloth set by end game.
What youre explaining also requires you to be in specific scenarios, such as having the witchcraft buff on you at all times and having shrug activated. What happens when neither of those things are available? You drop right back down to terrible magic defence and get blendered.