He should. They're stupid if they don't give it to him. He's owed one, and the guy reminded the whole friggin world what a real movie star can do when they're given a great part, great direction, and a green light.
I don't think he gets Best Director, deserved or not, because the Academy will generally split the big awards among a few films when there isn't a monumental film released in the calendar year (like the third LOTR, Titanic, Avatar). Its actually funny that Avengers: Endgame looks to be getting zero traction despite the record box office and fine craft behind it. It just shows you how much animus there is towards Disney and how little people in the industry rate their assembly line filmmaking.
Endgame too appears to be the victim of a pretty stacked year. I don't think it would have got nominated even if it was a weak year (much as I thought it was great), but I think 2017 and 2018 did not have the same level of clear best picture type nominees. I could be wrong, but that's the way I saw it.
Black Panther and Bohemian Rhapsody got best picture nominations last year to put it into perspective. In my view, Infinity War and Endgame were superior films to those. Significantly so.
Some may have not liked some of the award contender films of this year, but, at the end of the day, Scorsese and Tarantino, two of the best filmmakers of all time delivered two big, acclaimed films. Another very acclaimed director in Bong Jooh-Ho delivered one of the best reviewed films of the year.
I saw some other potential best picture nominees of the year- I found Joker to be very compelling (anchored, of course, by a terrific performance from Phoenix), 1917 is technically very impressive, Greta Gerwig's Little Woman was narratively and acting-wise easily one of the best films I watched this year. Uncut Gems was intense, gritty, and packed with strong performances.
When Endgame came out in April, I remember thinking that Disney would probably make the awards push, but, as these other films came out in the Summer and Fall, it became increasingly clear to me it was going to get boxed out.