Every Phase of the MCU has included at least one instance of the Avengers assembling, until Phase 4, and Hawkeye can explain why. Although the Avengers have faced massive world-changing events more than once, battling Thanos (Josh Brolin) for the infinity gauntlet in Avengers: Infinity War and Avengers: Endgame were arguably the most world-altering events the MCU has ever seen. By observing the MCU Phase 4 show Hawkeye, audiences can see why the Avengers won't assemble again until Phase 5, as they still have many mysteries to resolve from previous phases.
Hawkeye followed Clint Barton (Jeremy Renner) as he dealt with the repercussions of his actions during the 5-year break between the events of Infinity War and Endgame. After Thanos snapped half the universe out of existence, including Barton’s family, Hawkeye took on the guise of Ronin to take out his aggressions on the criminal underworld, brutally murdering his foes. After Black Widow (Scarlett Johansson) brought him back to the Avengers and the team defeated Thanos, Barton had to deal with the repercussions of his actions as Ronin and the loss of long-time friend Natasha—repercussions like Hawkeye's Tracksuit Mafia and Yelena Belova (Florence Pugh), which once again put his family at risk.
Hawkeye showed that the heroes of the MCU are still in the process of putting their lives back together after the events of Avengers: Endgame. Meanwhile, the world is simultaneously trying to cope with the post-Blip world crisis. There cannot be another major Avengers crossover until the dust has settled from the events of Avengers: Endgame. The audience needs a chance to catch up with each hero individually as they deal with the massive issues that affected their personal lives because of Thanos. The audience also needs to see how the snap changed the universe(s) that the Avengers exist within.
The events of Avengers: Endgame scattered and divided the Avengers. Three of the found members—Iron Man, Captain America, and Black Widow—are either dead or retired from superhero-ing. Hawkeye further demonstrated that many superheroes do not want to be active right now because they want to focus on being reunited with their families. Not only that, but numerous people are looking for someone to blame for the events of Infinity War and Endgame, as seen when Yelena tried to kill Hawkeye for failing to save Black Widow. Therefore, it may not be wise to assemble the Avengers and further complicate matters while each superhero is sorting out their personal problems.
Instead of focusing on assembling the Avengers, Phase 4 is sowing the seeds for Phase 5. Phase 4 focuses on how the Blip affected heroes the audience is familiar with while they introduced new heroes to the MCU. For example, Hawkeye showed Clint dealing with his issues leftover from Avengers: Endgame, while introducing Kate Bishop (Hailee Steinfeld) as a counterpart to Hawkeye. By the time Phase 5 arrives, audiences will be familiar with an entirely new cast of characters who can fill the gaps left by the losses in Endgame (and beyond).
While Phase 4 films like Spider-Man: No Way Home and Doctor Strange In The Multiverse of Madness showed the heroes of the MCU dealing with massive threats (including the multiverse twist), the Avengers cannot assemble just yet. Hawkeye demonstrated that every hero in the MCU has a lot on their plate right now, and if the Avengers assembled in a public manner then everything would become even more complicated and confusing for all involved. For now, Phase 4 is using shows like Hawkeye to demonstrate how the heroes are coping with the events of Avengers: Endgame, and laying the groundwork for a new team of Avengers to assemble in Phase 5 of the MCU.
