On further evaluation using the current criteria, Waver seems to work purely on the premise that he has allies. In any case that the plan falls apart and he is the lone survivor, he doesn't have any tools to win on his own. Especially with the nature of his NP as a debuff.
This is one of the stupidest things I've ever heard. By your logic, the only high tier servants are the ones that make excellent anchor servants -- and that's absurd, especially in the support unit meta that is Fate GO.