FWIW, this is on par with reviews for _anything_ in Japan.
The fanciest and most recommended ramen shops don't crack 3.9 on local review sites, the mindset is completely different from "oh nothing went wrong, 5 stars I guess!".
Ha, I'm reminded of reviews from Vietnam where you'd usually see restaurants get destroyed in reviews because they are 20 cents more expensive than some place else. Price was such a much bigger part of the review than other places I've lived.