This isn't how film criticism works though. Citizen Kane isn't held up as a great film because people said it was great and no one ever talked about the film again. Its held up as a great film because it inspires conversation and has done so for multiple generations now. This is the issue I have with how the MCU is discussed, how often does one say "I watched Ant-Man 2 yesterday, I liked it" and that's it in terms of actual dialogue regarding the film's content. Most MCU discussions tend to devolve into topics regarding how a film will affect future MCU films (DCEU fans do this as well, but not anywhere near the same extent).
I don't know how you can claim Snyder was abandoned when his fanbase successfully petitioned for his work can be completed. If you're a fan of Avengers, you should be a fan of Joss Whedon, but that doesn't seem to be the case. The MCU fandom seems perfectly content to never have Joss Whedon touch another MCU production, which is strange.
I also don't get what you mean when the Russo brothers 'perfected' Joss Whedon's work (I can say a lot by the way, about your word choice. I don't even think Citizen Kane stans throw out the 'p' word that often). The Russo brothers errata-ed huge portions of Joss Whedon's character building in Winter Soldier;
>>>> Why is Captain America a member of SHIELD in WS, when he refused to become a member in Avengers and was provided every reason not to join in Avengers? Hording hydra tech, SHIELD trying to nuke New York, I think there were some other reasons too
>>>> Why did the Russo brother's abandon Joss Whedon's characterization of SHIELD? They were clearly based upon conspiracy theories about 'global elites' controlling the world as evinced by their callous decision to NUKE New York City. In WS, the 'illuminati' board members are treated like benevolent CEOS who've always tried to do right, even though they should clearly be arrested.