Yes, the age of legends is the same trope, but I don't think the rest matches.
There is one Big Evil but the lesser ones are all scheming against each other. In Tolkien there's just a bit with Saruman and the spiders, but you don't really have factions amongst the ringwraiths, for example. It's all just a battle between Sauron/everyone or Melkor/everyone.
The good ones in WoT don't simply start separated but actively hating and fighting each other, Rand has to go to war with many nations and specific groups within nations, and some of them just split and start killing each other. This is not the same as Gondor and Rohan being on bad terms, or some elven clans just standing on the sides.
In Tolkien's universe you 99% of the time know who is evil and who is not (elf, dwarf, hobbit, ent, eagle, northern man = good; orc, goblin, troll, dragon, great spiders, eastern man= bad).
Yes, a couple human characters are ambiguous, but it's a pretty small minority.
In WoT you have a couple evil races and you, the reader, have a clear view of who is good and who is bad.
But in-world people want to kill other people because each thinks the other is evil: that looks a substantial difference to me.
Re: pure heroes, I meant that the main characters basically are all 100% good. This is the same in both universes too, just not a constant in all high fantasy. At least I think, I didn't finish the wheel of time ;)