In real English, as native speakers and good writers use it, allows "which" as as "that" in restrictive relative clauses (although it no longer allows "that" -- only "which" -- in supplementary clauses). See http://itre.cis.upenn.edu/%7Emyl/languagelog/archives/001464... ("although there is a clear frequency difference between the dialect groups [British and American English], ... both that and which are grammatical in integrated relatives in both dialect groups"). The rule is one made up by grammar checkers and authors of pedantic pamphlets, and if it's distracting to you I suggest you go cold turkey and read fewer of those and more of just about anything else.
Those are exactly the "grammar checkers" and "pedantic pamphlets" that I referred to (Grammarly is literally a grammar checker). Why should we consider them right and Brontë, Dickens and Melville, and their editors, wrong?
That is not purely a rhetorical question. While I do think that Brontë, Dickens and Melville are right and the authors of your links are wrong, I also would like to know why you and many others think it's the other way round.
Not OP, but I wonder if his/her brain is similar to mine: I get a small kick of dopamine from knowing that I do something "technically right" that others (especially famous people) do "wrong."
