Not specific to this manga (I like it), but I disagree with that opinion.
When you as a writer, artist etc. make your works public, you are also exposing them to public opinion and criticism, and should be aware of and prepared for that.
Also, readers won't know if it's high or low quality conent and writing or whether it's to their taste, if they don't read the story.
If you assume you're going to like everything you're going to read, you're bound to be disappointed. And if you force yourself to like it anyway, you're just lying to yourself.
Expressing your opinion about a story, characters motivations etc. is a way to process what you've read and is a natural reaction.
Now, we can always discuss what type of tone should be used, when critisizing other's hard work, or genuine attempts at creating art. But saying one should not express their opinion at all, is francly unrealistically idealistic and furthers no goal but oppressing critical thinking.
I saw alot of comments complaining about the ML and FL like...wth? Its the author choice that they make them like that, and WE are just a READER, so we should respect the author wants. And PLEASE REMEMBER that we are not the one who is making this story, Its the author :)