Nothing is complicated or controversial...until you decide to disagree with it. And I do in fact think that the argument you are supporting is presented as being prima facie correct, and therefore not in need of substantiation.I think "intentions" wasn't quite the right word to use, but what DracoSuave is describing shouldn't be that complicated or controversial. What he is saying is that a proper "controller" spells provides a lot of freedom in how you can apply a condition, whereas proper defender, striker, and leader powers may apply the same conditions, but do so under a more restricted set of triggers or options.
Personally, I see classes of other roles throw out effects that exert extreme and unrestricted degrees of control all the time. Even in a controllerless party, we'll have multiple blind, dazed, prone monsters at any given time.
Doesn't a controller apply conditions in ways that help other players?A proper leader power applies the condition, but in a way that heps other players. I.e. powers that knock enemies prone next to the defender, or makes them grant CA to the striker.

In addition, I would like to see controllers on the whole have good access to interrupts. And I would like to think that the controllers should have preeminent access to conditions that other classes have only in fairly exceptional cases, such as stun and dominate. But neither really seem to be the case.I think that the controller role is the least well defined, and instead of looking at "what do current controllers do?" the question should best be put as "what should controller do?" I think the two simplest answers are:
1) Apply damage to multiple targets
2) Apply a variety of harmful conditions to enemies
You might add:
3) Modify the terrain, and/or the placement of enemies and allies