Probably not, given the way the whole Order thing works, but that’s not the point. This is: since when has this kind of power been the mightiest in the Warcraft universe? 
If anything, some Death stuff probably would be, as declared or prophesied on a few occasions, although apparently balance has been maintained in the end.
Another counterexample: Aman’Thul’s protégé on Azeroth, i.e. Nozdormu, wasn’t even the strongest of his kind or their leader.
Yeah, the oldest, as I’ve also written, and their ‘daddy’ of sorts, what of it?
Boris Spassky, for example, is the oldest living world champion in chess, doesn’t at all mean he’s the best right now, especially at his venerable age.
So, still no argument to back this claim up, sorry.
On the other hand, from what I’ve heard, there’ve been hint that Azeroth is potentially the strongest ever — although she hasn’t hatched from the planet yet… And I suppose I could dig up some lore to support it.
In other words, you’re proud of having nothing intelligent to say here. Well, this seems to be rather trendy nowadays. 
People are proud of many things they should or used to be ashamed of — including their stupidity, even…
Yeah, I know, repeating myself yet again.