> I hate articles like this because they present highly opinionated solutions as something definite even though it has a narrow focus on what the author cares about.

Whatever the author says about custom scrollbars isn't going to stop CSS-Tricks from styling their scrollbar. The article is perfectly fine because programmers are free to ignore it, and if this article convinces even one programmer to switch from a custom scrollbar to a non-customized scrollbar it's likely they never needed it anyway.