You also gotta consider the fact that the Wu clan is literally universally considered by other nobles (who make up most of the sect) to be complete and utter bums run by an alcoholic lecher who isn't even a Shangtian. And bear in mind that they don't even know it's not his fault.
Now take the Wu Heir - he is considered to be the child of a lowborn maid by the vast majority of people, comes into the tournament poor as hell with only his dad's pissstained robe (if even that), and then apparently everyone must now believe that this waste of noble blood is supposed to be 100% BP and equal to TW himself, when there is a shining figure in the form of Prince Ruo who everyone already knows is a complete genetic and alchemical experiment, raised by two Shangtian's one of whom is the strongest one ever on top of being the Emperor of their country. He behaves like a dignified and intimidating prince to those he deigns to speak to, completely ignores others, and also is fighting people above his stage a month or two after arriving to the sect.
While the Wu Heir by that point has one fluke (to them) mid-battle advancement victory, which is to them unfair as hell. And even considering the fact that the Wu Heir can advance to MH literally within a month of becoming EH, he doesn't show anything comparable to Ruo who doesn't even need to be a MH to fight them, and then when he fights a semi-strong LH he beats his *** with his OWN proprieatary clan/personal technique after also advancing mid-battle (which doesn't seem unfair since the opponent is still of a higher stage AND because to them it just reinforces the cognitive bias).
For AC I think you're right, but the situation is also very different. First of all most Cultivators there aren't nobles but Warriors who for all their faults still respect strength more than status (at least the normal ones), the fact that Anon literally said that the MC has plot armor and makes it a point to state that the MC just happens to arrive to a gate at the most opportune moment (before the Foundation change), and after the Foundation change you get help with 10 billion different strings attached and only because the world saw you beat the prospective Top 1 contender at the time whose reputation had him up on the highest pedestal.