nah, not true at all.
Sure, it takes some time and switching--but Chaos Storm + iWarlock + switch to sword/focus + Blurred Frenzy + iWarden = rather massive damage gives you multiple skills that pump out rather substantial damage.
But yeah--lots of CD to recycle it, and you still spend time kiting. Also, Mesmers have rather "elite" downed skills

, so there's a rather substantial array of damage in various states....just have to be smart about playing. Yeah, we can't just run in and go smashy smashy aggro everything until we have to wait for someone else to come res us for our stupidity, but...you know. That's what warriors excel at.
the sword skills provide you a decent amount of invulnerability, and good escape with good CD--you need it of course. Mesmers certainly can't stick around within a mob, but the burst damage is pretty good if specced for it. I am having problems with iWarlock, though, where after activating, it only seems to cast half the time--this is very annoying. the skill activates and flashes, then simply doesn't cast. I have nothing else activating and the target is still very much alive, so I have no idea what is going on with that. Shame, those little bastards are doing roughly 4k damage each for me on critical.

I'm not even specced anywhere close to where Mr Moneybags Poly is specced, either.