The author of the article is very biased because he is also the (co-)author of these libraries.
Personally I think that is not the fine way to bash other projects in the open source community. Clearly, attrs+cattrs and pydantic focus on different things. Let us all live together peacefully :)
To your first point, that's the third sentence of the article itself.
To your second, I struggle to see this as bashing. It's certainly not an objective comparison, but it is about as even-handed a comparison as I'd be willing to ask of a mere mortal when they're also personally invested in the subject. You don't see sentences like, "Pydantic is wrong!" you see ones like, "Pydantic is very opinionated about the things it does, and I simply disagree with a lot of its opinions," or, "I disagree with this. Un/structuring should be handled independently of the model." That's not bashing; that's constructive criticism. It's worth noting that he also acknowledges that Pydantic does some things better.
For my part, I think my only real complaint about this article is that he doesn't really pay enough attention to the fact that, despite their overlapping functionality, (c)attrs and Pydantic are optimizing for very different use cases. That leaves me thinking that some (though far from all) of his criticism has a certain, "This screwdriver isn't very good at driving nails," characteristic.
Personally I think that is not the fine way to bash other projects in the open source community. Clearly, attrs+cattrs and pydantic focus on different things. Let us all live together peacefully :)