It very neatly describes the way liberals see the world and political struggle.
Lots of people complain about the anti-climatic ending, but really I don't think it could any other way. I'd like to imagine that there's some alternate universe where Kōhei Horikoshi actually believed in something and Deku was actually built up as the anti-All4One he was only hinted as being in the beginning of the story. Where he opposes all the many injustices of the hero world and determines to change their frequently backwards, insular, contradictory society for the better, and forms his own faction antithetical to the League of Villains and when he finally has his showdown with All4One, Harry surpasses by adopting new methods, breaking the rules and embracing change and the progression of history. While All4One clings to an idyllic imagining of the past and the greatest extent of his dreams is to become the self-appointed god of a eternally stagnant Neverland. Deku has embraced the possibility of a shining future and so can overcome the self-imposed limits All4One could never cross, and All4One is ultimately defeated by this.
But that would require a Deku that believed in something. and since Kōhei Horikoshi is a liberal centrist Blairite that doesn't really believe in anything, Deku can't believe in anything. Deku lives in a world drought with conflict and injustice, a stratified class society, horrendous oppression of the heroes with ugly quirks, the absurd charade the hero world puts up to enforce their own self-segregation, a corrupted and bureaucracy-chocked government, rampant racism, so on and so forth. But Deku is little more than a passive observer for most of it, only the racism really bothers him (and then only racism towards quirk people). In fact, when the Meta Liberation Front stands up against the institutionalisation of dangerous quirk holders and even segregation based on quirk, they're depicted as some kind of evil for doing so. For opposing segregation. In the end, the biggest advocate for change is All4One and Deku and friends only ever fight for the preservation and reproduction of the status quo. The very height of Deku's dreams is to join the heroes, a sort of FBI and the ultimate defenders of the hero world status quo. One4All and the League of Villains are the big instigators of change and Deku never quite gets to One4All's level. Deku doesn't even beat One4All, One4All accidentally kills himself because he violated some obscure technicality where his own arrogance causes him to rewind himself out of existence.
And this is really the struggle of liberals, they live in a world fraught with conflict, but aren't particularly bothered by any of it except those that threaten the multicultural pluralism. They see change, and the force behind that change, as a wholly negative phenomenon. Even then, they can only act within the legal and ideological framework of their society. So for instance, instead of organizing Insurrectionary and disruptive activity against Trump and the far-right, all they can do is bang their drum about what a racist bigot he is and hope they can catch him violating some technicality that will allow them to have him impeached or at least destroy his political clout. It won't work, it will never work, but that is the limit of liberalism just as it was the limit of My Hero Academia.
While it doesn't provide a roadmap or explain it as much as we might like, the manga is pretty heavy-handed with explaining that a large part of the direct social basis for that kind of behavior was the effect of All Might, Mr. "Everything will be okay, because I am here!" aka the "Symbol of Peace," the man upon whom the entire public confidence rested. The central issue of the narrative in the broadest sense is that the Symbol of Peace was not a great means of social stability and was more a tool for cultivating misbegotten social confidence based on literally lying to the public, which then produced imitators who were liable to get themselves killed like Deku almost did, along with lacking proper solidarity. Though All Might survives to the end of the manga, he explicitly narrates that "The Symbol is dead" and that his paradigm has been replaced by that of the new generation and a more cooperative and mutual attitude toward protecting the population. This is part of the narrative reason that One for All is torn apart over the course of the final struggle and just dissolves, because All Might has positive aspects of his legacy that he passed on, but the singularity of his person as the Symbol of Peace has been surpassed with this new cooperative attitude rather than passed on to some new Great Man. There will never be another All Might, and that's a good thing.