Given that they might as well just go to a thumbs-up/thumbs-down system. There are a number of situations where I'd love to give somebody 4 stars as a way of saying "You did good but I'd prefer X", but I don't want that to be a black mark.
I make the same mistake some times. If all other things are equal on a product I'll pick the 4.8 star one over the 4.6 star one, even though I know perfectly well that these are worse than useless.
That's no excuse for an author to be a dick about it, but it's a really stupid bind they're caught in.
A star rating system I know of that makes sense and is relatively uncontroversial is the independent groups like AAA hotel ratings, where the number of stars is more-or-less objective based on the amenities, making them more of a classification than a rating.
Blogs are also social media, this is just additional pile-in. I think this is supposed to be better because it uses too many words, tries to make the personality flaws that it ascribes to reviewers universal, and has a bunch of emotionally performative talk about moved to tears and having your heart broken mixed with talk about trauma.
edit: maybe the blog author should spend the time to listen to the life stories of the people who review books. If there were a more traumatic story from one or more of them, expressed well, would they win the sympathy contest?