I'll give you an Upvote. I agree. I argued this both times they buffed his damage. His win rate is NOT correlated with his performance. His win rate is correlated with the conundrum that helping a team versus split pushing a lane are contradictory objectives, and his kit has a built in split pushing incentive, forcing a playstyle for the majority of every game, even if that isn't the best idea.
Unlike Tryndamere and Yorick, who can roam and do their split push while basically rushing minion waves and eliminating them to get to a turret, Nasus has to go slow to ensure Q's. This deprives him of the capacity of ress timers/counterplay to do what they do: Push lanes while also contributing to a team. Nasus does one or the other.
He can have 2000 stacks and still lose a game, simply because it doesn't usually change the outcome of a fight vs champs who are competitive vs him. It only affects teams who are poorly built, who face tank, one after another. Which...... as you go up tiers..... happens less and less.