Yes, this is a masterpiece. It's careful enough to not engage in finger-wagging, it's not judgemental, it doesn't make the other side sound evil, even though it has a side. We can see on facial expressions, on the emphasis on the absurdity, that the author has a position and is arguing it with his work.
Works of art, especially for entertainment, don't need to have a thesis to be great. Controversy is not a condition for quality. But when they do have a thesis, and it is honestly conveyed without sophistry or romanticism, it's all the more enjoyable.
It's a pity that I don't live in Japan and don't know how much of this depiction is true, or how much it is stretching reality to caution mangaka and readers of where the slippery slope can lead. I would very much like to know what is on the gravestone of manga stores nowadays. While I don't really like reading about harsh themes like domestic violence, I'm sure once a society decides to ostracise some of their creators for specious reasons, much interesting stuff is produced in ostracism.