Why not? Yato is the perfect filtering tool for Sasuke, not only has he defeated him, but he is also strong enough to grow and continue to maintain a degree of challenge to Sasuke before Sasuke destroys Itachi.
This is really strange, but it perfectly portrays what life would be like for someone who has lived thousands of years (I don't think anyone could maintain their sanity after countless years)
Then. I also thought she/he is only judging by their political ideals. Anyway, the fanfic is not 5 stars, but a one star rating is a disgrace to the author's effort.
Coming back here after reading the entire fanfic, it's not really very good, but it's not bad enough to be worth just one star. I believe you shouldn't use your political ideals to judge this.