This is like OPM except MC's only trait is being strong and brainless. He has no goal to chase after and no sign that he will grow nor change himself which the story has to spin him around to give him something to do. In sort, he has nothing to offer to the readers because that's his character. At least Saitama still show displeasure when face with some BS.
And side characters instead of having their own development to drive attention away from the blank MC, only perform action within the personality and traits that the author establishes for them within 5 minutes, I.e bitch noble be bitchy, expositor gotta exposition, genocide bomber be cheerful.
...ok, may be not the last one.
Story is all over the place, characters just show up and declare marriage with the person next to them like it's post mating season even though there's no build up or anything then sprinkle in the political drivel that everyone totally love.