Simply put, it’s not a good article.
What does "heavily biased" mean in this context? It's a straightforward article that puts forward a position, a series of propositions supporting that position, and a potential solution.
It's biased in that the author has an opinion he's trying to convince people of by providing arguments in its favour, but that's what writing tends to do (including your comment).
The "banning" stuff is obvious hyperbole[0]. No reasonable reader could conclude the writer means CSS margins should be banned in law.
Any article stating something should be “banned” can’t really be described as a balanced discussion about the usage of that thing.
I’m all for discussions on why usage of something is bad but in the case of margins there’s clearly use cases that are suited to it, which other commenters have highlighted but which the article entirely glossed over.
So the article is more than just written as a persuasive piece; it misses any balance or contextual clarity and thus ends up dishing out bad advice as a result. Bad advice that is so strongly emphasised that lesser experienced developers would easily be intimidated by it.
Now if people want to discuss the strengths and weaknesses of margins and put forward alternative solutions in the process, that at least informs lesser experienced developers about ways to solve their real world problems rather than berating them for not following some misguided idealised view of perfection.
(Yes I know there was some details about alternative ways to implement a margin, but they were crap and lacked any detail, since the article was essentially a rant piece rather than technical document)
