Ultimately, My Hero Academia's fictional world has descended into chaos as a result of the villains' repeated attacks. The Hero Association is no longer able to keep up with its illicit behavior, which has caused turmoil across the nation. Even worse, after Dabi's identity was revealed, Endeavor, the current No. 1 Hero, is depressed. The heroes are therefore compelled to use drastic means to try to protect as many innocent people as they can. But Midoriya has other ideas. He uses well-known personalities to help him go rogue, always improving himself and his quirks in the process. His most recent level-ups demonstrate how he and Shigaraki are now the two sides of the same coin.
Most of the offenders who have escaped Tartarus are left to their own devices. Most of them have reverted to their evil ways, while some have even allied themselves with All For One. With the increase in crimes that go unpunished, the villains that lurk among the populace now feel more confident enough to show themselves. As a result of the heroes' inability to keep up with the increasing number of crimes, their already meager staff eventually becomes even smaller. The Hero Association has already selected a number of locations as shelters and is concentrating its resources on providing security for them.
Midoriya is searching for bad guys
Knowing that Shigaraki and All For One are constantly tracking and searching for his location, Midoriya opts to leave his loved ones and goes rogue. He lurks around the chaotic, almost dystopian landscape, trying to do as many heroics as he can. He fights off villains trying to sow terror, especially notable ones that have escaped Tartarus. In addition to that, he also tries to save and rescue as many civilians as he can. However, given that he's constantly moving, he doesn't see his actions through to the end. He simply leaves the rescued civilians in the hands of other heroes or bystanders after eliminating all threats and continues on his way.
Midoriya isn't just in a never-ending and futile pursuit of minimizing casualties. While catching villains and rescuing civilians, he is also constantly honing his Quirks. His rogue operations are being supported not only by All Might but also by Endeavor, Hawks and Best Jeanist. This allows him to coordinate his actions with almost no delay. Moreover, that's not all the help he gets. Deku has also managed to awaken the ability to be in contact with the previous One For All users at all times. Now, all the previous users are aiding him to master their respective Quirks. Deku's heroic operations serve as the perfect practical application and training for these Quirks.
Shigaraki's struggles are what Midoriya is going through
As All for One's protégé and inheritor, Shigaraki has been under the villain's tutelage since the beginning of the series, as All For One has been grooming Shigaraki to become the perfect vessel. This includes making him stronger, and recently, even granting him multiple Quirks. Unlike Midoriya's newly awakened ability to communicate with his predecessors, Shigaraki has always been able to speak with All For One. In fact, that's basically how All For One indoctrinated the young villain, as his original body was being held captive in the deepest confines of Tartarus.
Despite the similarities between their experiences, they also contrast sharply. One For All's former owners were deeply respected by Midoriya, and the reverse is also true. As a result, Midoriya's forefathers only desire for the young hero to master and possibly develop their Quirks. Shigaraki and All For One, regrettably, fall short in this regard. This contrast demonstrates why Shigaraki and All For One are, respectively, the main hero and villain of My Hero Academia. Shigaraki not only despises his mentor and master, but All For One is also continuously attempting to take over his student's body.