I think the reason Roma, The power of dog, or 1917 failed to prevail as the eventual winner, is largely attributable to the fact that they are the movie that people respect, appreciate or admire, rather than loving them to the heart. Parasite, Coda or Green book are the kind of movie that voters love it genuinely, despite knowing their flaw. Voters are known to vote with their heart and if one really love a movie from the bottom of their heart, no way they are placing them at the bottom tier.