Straw man. Author didn't say criticizing a language's flaws at all is problematic. Dismissive, arrogant, "X language sucks and so do people who use it" language is problematic.

It can be boiled down to the difference between constructive criticism vs. bullying. One is productive, the other just serves to make the person saying it feel better and reinforce exclusivity and an air of superiority.

Perhaps indirectly. Though that's not the focus of the article. Rather that language/platform gatekeeping is counterproductive and harmful to growing the community.