Hate me for it, but they didn't. Maybe The Dark Knight deserved recognition in the BP category but other than that, I don't know of any other blockbuster in the last few years that deserved that honor and didn't get it.
They were willing to nominate blockbusters and did it (Avatar, The Martian, etc.), but all the superhero movies everyone wants to get nominated just weren't good enough imho. Critics seem to agree, because no single one got more than 80% on metascore since TDKR, except for Black Panther.