you are wrong, the wladimir has not beat wilder, stiverne, fury, jennings, apple, chisora, ruiz, and others although i am sure he shall beat these guys after fulfilling mandated obligations but still he hasn't done it yet.
The andre ward has not beat groves, chavez, dirrel and is using the promoter conflict for a good excuse to avoid the dangerous fighters/ moving up to fight adonis, kovalev, hopkins
no fighter has cleaned out.
You are nitpicking, man. By your logic no one even cleaned out any division. There are always new contenders. Groves and Jr. emerged after Ward had cleaned out the SMW division. As for Dirrell, he beat the guy who beat the guy (and no, Froch vs Dirrell was no robbery) and one-upped Dirrell vs Abraham. That has to be good enough, no one fights literally everyone. And what does not wanting to fight the best 175 pounders have to do with whether he cleaned out the 168 division or not?
Wlad's situation is a little trickier because he had to share the few worthy HW challengers with his brother. Between them they did beat everyone that mattered: Byrd, Brock, Brewster, Haye, Chagaev, Chambers, Pov, Adamek, Arreola, Gomez. They didn't fight Valuev and Ruiz, but again, Wlad beat the guy who beat these to (Haye). The contenders you listed emerged later.
To answer OP's question: maybe Darchinyan at 115. He beat Kirilov, Mijares (P4P player at the time), Arce and a couple of other decent guys. He didn't fight Montiel though.