Hamilton is one of the biggest movies of the year, and honestly, that would likely be the case even if 2020 had the level of competition we were actually expecting it to have. However, it's possible that one of the most well-regarded movies of the year won't be recognized at the biggest awards show of the year, as the Academy of Motion Picture Arts & Sciences has found that the movie is ineligible in the documentary film category. However, that apparently won't stop Disney from submitting the film for Oscar consideration via other means.
According to Vanity Fair, an AMPAS rule from 1997 would make Hamilton ineligible in the documentary film categories as the rule disqualifies films which are "works that are essentially unfiltered records of performances." This would make Hamilton which is a filmed production of a stage play, unable to compete. However, even if Hamilton can't compete for that particular award, it seems Walt Disney Studios is planning to still submit the film to the various guilds that make decisions regarding other awards, as the qualifications for nomination vary between guilds and thus Hamilton might still end up in the running for those other awards.
And Disney is expected to still submit the film to the Academy as well, thus it will have to make an official ruling on eligibility. Even when it comes to the documentary award, there's still a chance that Hamilton could qualify. A handful of "concert films," like Spike Lee's The Original Kings of Comedy, have been considered for Oscars in the past because they had sufficient creative contributions that made them more than simply recordings of performances, but the same is technically true of Hamilton. While the bulk of the film is made up of two live performances which were recorded., the close-ups, which could not have been captured on stage without disrupting the performance, were filmed separately. The question seems to be, are those creative contributions enough to get consideration.
Hamilton certainly blurs a lot of lines and so it's understandable if the Oscars aren't quite sure what to do with it. At the end of the day, Hamilton is a stage musical, which has already won its share of Tony Awards, and it feels a little out of place to see a filmed version, essentially the identical show, show up at the Oscars and start taking film awards too.
At the same time, the experience of watching Hamilton on Disney+ isn't the same experience you would have sitting in the theater. People worked on making this production of the show a success as a movie. Cinematographers and editors made the same creative decisions filming Hamilton that they would have on any other film production, and those people should have a chance to be recognized for what they have done.
The 2021 Oscars are going to be...interesting, for a number of reasons, which honestly might give Hamilton a shot at greater consideration that it might have received had it been released theatrically in 2021 as originally planned.